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11. |
Reaction of Anthranilic Acid with Orthoesters: a NewFacile One-pot Synthesis of 2-Substituted4H-3,1-Benzoxazin-4-ones† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 286-287
Mohammad S. Khajavi,
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摘要:
CO2H NH2 + RC(OEt)3 or RC(OMe)3 a R = Me b R = Ph c R = Et a R = H b R = [CH2]2Me c R = [CH2]3Me 2 3 N O O R 4a–f RC(OR¢)3 + H+ RC(OR¢)2 + R¢OH + R¢ = Me, Et CO2H NH2 + RC(OR¢)2 CO2H N H OR¢ OR¢ R N –R¢OH O O H OR¢ R H+ 5 NH O O OR R H+ –R¢OH 4 H+ –H+ + 286 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 286–287† Reaction of Anthranilic Acid with Orthoesters: a New Facile One-pot Synthesis of 2-Substituted 4H-3,1-Benzoxazin- 4-ones† Mohammad S. Khajavi,* Nasser Montazari and S.S. Sadat Hosseini Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran, Iran The synthesis of 2-substituted 4H-3,1-benzoxazin-4-ones by the condensation of anthranilic acid and orthoesters under classical heating and microwave irradiation is described. 4H-3,1-Benzoxazin-4-ones are valuable starting materials for the synthesis of a variety of 2,3-disubstituted quinazolin- 4(3H)-ones.1–5 A number of synthetic methods for the preparation of 2-substituted 4H-3,1-benzoxazin-4-ones have been described: (i) cyclodehydration of N-acylanthranilic acids by acetic anhydride;6 (ii) reaction of anthranilic acid with acid chlorides in pyridine;7 (iii) treatment of methyl N-aroylanthranilates or methyl 2-ureidobenzoates with concentrated sulfuric acid;8 (iv) photoisomerization of 2-arylisatogen. 9 Here we report a new general and highly efficient method for the synthesis of benzoxazin-4-ones by the condensation of anthranilic acid with orthoesters under classical heating or microwave irradiation (Scheme 1).The desired reaction occurs by refluxing a variety of commercially available orthoesters 2a–c and 3a–c with anthranilic acid under dry conditions. A number of benzoxazin- 4-ones with various substituents were thus prepared in high yield, see Table 1. To the best of our knowledge, there have been no studies on the synthesis of this heterocyclic ring system using anthranilic acid and the orthoester condensation methodology. In each case, the reaction was carried out using 20 mmol of anthranilic acid and an excess (1.5–4 equiv., Table 1) of the orthoester.In all cases, the products 4a–f precipitated from the reaction mixtures and were purified by recrystallization. This reaction proceeds without organic solvent and in the absence of some types of basic or acidic catalyst. Furthermore this method is suitable for the preparation of 2-aryland 2-alkyl-4H-3,1-benzoxazin-4-one and also for the unsubstituted parent heterocycle 4d.The reaction seems to proceed through the intermediacy of the imidic ester 5 which undergoes nucleophilic attack by the carboxyl oxygen to produce the cyclized product with the elimination of a molecule of alcohol. Furthermore, we examined this reaction under microwave irradiation and it was found that the condensation of anthranilic acid with the orthoesters 2a–c or 3a–c results in the rapid formation of the benzoxazin-4-ones 4a–f in high yield when the reactions were conducted in open vessels in a microwave oven.The reaction was performed in a beaker covered with a stemless funnel and to control the reaction the irradiation was carried out in two stages with a cooling period between each irradiation. In some cases, to optimize the yield for each irradiation sequence, a different power was used (Table 1). In general, the reaction in the microwave oven was highly accelerated. The results are summarized in Table 1.*To receive any correspondence. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Scheme 1 Table 1 Reactions of anthranilic acid with orthoesters Classical heating Irradiation conditionsb Orthoester Lit. mp Entry Product 4 R (equiv.) t/min Yield (%)a (1) P/W t/min (2) P/W t/min Yield (%)a Mp (T/°C) (T/°C) 12 34 56 a b c d ef Me Ph Et H Pr Bu 2 1.5 24 22 90 60 90 120 90 90 87 91 83 80 78 75 210 210 210 210 210 210 32 35 34 210 385 210 385 210 210 34 31 35 90 94 82 76 80 83 80–82 123–124 84–86 43–44 58.5–60 41–42 80–816 124–12510 123–1246 85–866 43–44.46 43–4511 59–606 — aYield of pure, isolated product based on anthranilic acid.bTo control the reaction the irradiation was carried out in two stages, with a cooling time between each stage.J. CHEM. RESEARCH (S), 1997 287 The structures of compounds 4a–f were confirmed by IR, 1H and 13C NMR spectral analyses (Table 2) and their physical properties were identical with those of authentic samples prepared by reported procedures.6 In conclusion, we have demonstrated that orthoesters and anthranilic acid condense under conventional thermal heating or microwave irradiation, providing an efficient and convenient synthesis of 2-substituted 3,1-benzoxazin-4-ones. In this method, orthoesters serve as a ‘one-atom linchpin’ to form the corresponding benzoxazin-4-one.The extension of this reaction to the synthesis of other heterocycles is currently under investiation. Experimental IR spectra were recorded as KBr pellets on a Shimadzu IR-470 spectrometer. NMR spectra were obtained on a JEOL-EX-90 instrument at 90 MHz and 22.63 MHz for 1H and 13C, respectively. Microwave irradiations were carried out in a National oven, Model 5250, at 2450 MHz. Melting points are uncorrected. For safety reasons all the experiments with microwave ovens should be performed in an efficient hood in order to avoid contact with vapours.All products (except 4f) are known compounds and their physical data, infrared and NMR spectra were identical with those of authentic samples. Preparation of 2-Substituted 4H-3,1-benzoxazin-4-ones under Classical Heating. General Procedure with 2-n-Butyl-4H-3,1- benzoxazin-4-one (4f).·A stirred mixture of anthranilic acid (2.74 g, 20 mmol) and trimethyl orthovalerate (6.49 g, 40 mmol) was heated under reflux for 1.5 h.After this time the reaction mixture was cooled to 0 °C and the white precipitate thus obtained was filtered off and recrystallized from heptane to give colourless needles of 4f in 75% yield. General Procedure under Microwave Irradiation with 4H-3,1- Benzoxazin-4-one (4d).·A mixture of anthranilic acid (2.74 g, 20 mmol) and trimethyl orthoformate (8.49 g, 80 mmol) contained in a tall beaker was placed in the microwave oven and the beaker was covered with a stemless funnel and irradiated for 5 min at 210 W and then for 1 min at 385 W.The reaction mixture was allowed to cool to room temperature and the resultant residue recrystallised from dry heptane to afford the pure 4H-3,1-benzoxazin-4-one (moisture sensitive, very hygroscopic) in 76% yield. Received, 17th January 1997; Accepted, 21st April 1997 Paper E/7/00411G References 1 C. Parkanyi, H. L. Yuan, B. H. E. Stromberg and A. Evenzahav, J.Heterocycl. Chem., 1992, 29, 749. 2 V. K. Rastogi, S. S. Parmar, S. P. Singh and T. K. Akers, J. Heterocycl. Chem., 1978, 15, 497. 3 L. A. Errede, J. J. MeBrady and H. T. Oien, J. Org. Chem., 1977, 42, 656 and references cited therein. 4 M. J. Kornet, T. Varia and W. Beaven, J. Heterocycl. Chem., 1983, 20, 1553. 5 S. S. Parmar, K. Kishor, P. K. Seth and R. C. Arora, J. Med. Chem., 1969, 12, 138. 6 D. T. Zentmyer and E. C. Wagner, J. Org. Chem., 1949, 14, 967. 7 D. I.Bain and R. K. Smalley, J. Chem. Soc. (C), 1968, 1593. 8 E. P. Papadopoulos and C. D. Torres, Heterocycles, 1982, 19, 1039. 9 D. R. Eckroth and R. H. Squire, J. Org. Chem., 1971, 36, 224. 10 J. L. Pinkus, H. A. Jessup and T. Cohen, J. Chem. Soc. (C), 1970, 242. 11 O. Meth-Cohn, H. Suschitzky and M. E. Sutton, J. Chem. Soc. (C), 1968, 1722. Table 2 Physical data for compounds 4–f vmax(KBr)/cmµ1 Compound 4 C�O d (ppm) (CDCl3–TMS) a 1762 1H 2.46 (s, 3 H, CH3), 7.42–8.31 (m, 4 H, Ar-H) 13C 20.85 (CH3), 116.21, 125.90, 127.65, 127.86 (4 CH), 135.96 (C10), 145.98 (C5), 158.97 (CO), 159.74 (C2) b 1768 1H 7.24–8.35 (m, 9 H, Ar-H) 13C 116.62, 126.80, 127.73, 127.86, 128.02, 128.26,29.81 (9 CH), 132.13 (C-Ph), 135.96 (C10), 146.46 (C5), 156.52 (C2), 158.80 (CO) c 1758 1H 1.38 (t, 3 H, CH3), 2.77 (q, 2 H, CH2), 7.38–8.21 (m, 4 H, Ar-H) 13C 9.44 (CH3), 27.36 (CH2), 116.17, 125.82, 127.29, 127.49 (4 CH), 135.55 (C10), 145.73 (C5), 158.68 (CO), 163.08 (C2) d 1755 1H 7.45–8.42 (m, 5 H, C2-H, Ar-H) 13C 118.86, 127.08, 128.64, 129.20 (4 CH), 136.61 (C10), 145.45 (C5), 149.73 (C2), 158.36 (CO) e 1762 1H 1.24 (t, 3 H, CH3), 1.83 (sextet, 2 H, CH2), 2.72 (t, 2 H, CH2), 7.32–8.28 (m, 4 H, Ar-H) 13C 13.47, 19.50, 36.52 (3C-aliphatic), 116.78, 126.43, 127.98, 128.26 (4 CH), 136.28 (C 10), 146.38 (C5), 159.66 (CO), 163.00 (C2) f 1765 1H 1.02 (t, 3 H, CH3), 1.22–1.98 (m, 4 H, 2CH2), 2.79 (t, 2 H, CH2), 7.38–8.35 (m, 4 H, Ar-H) 13C 13.72, 22.23, 28.17, 34.49 (4C-aliphatic), 116.90, 126.56, 128.02, 128.31 (4 CH), 136.33 (C10), 146.51 (C5), 159.26 (CO), 163.24 (C2)
ISSN:0308-2342
DOI:10.1039/a700411g
出版商:RSC
年代:1997
数据来源: RSC
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12. |
Coupling Allylation of Dialkylselenaethenylboranes to give1,1- and(Z)-1,2-Dialkylselenapenta-1,4-dienes† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 288-289
De Yu Yang,
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摘要:
H RSe BR1 2 SeR RSe RSe Cu H H RSe Cu SeR i, NaOMe ii, CuBr•SMe2 iii, CH2 CHCH2Br –15 °C H RSe CH2CH SeR CH2 CH2 CHCH2Br –15 °C RSe RSe CH2CH H CH2 CH2 CHCH2Br –15 °C 2 3 1 + H RSe BR1 2 SeR RSe RSe BR1 2 H RSe BR1 2 –RSeH RSeH 288 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 288–289† Coupling Allylation of Dialkylselenaethenylboranes to give 1,1- and (Z)-1,2-Dialkylselenapenta-1,4-dienes† De Yu Yang,*a Yi Zhangb and Xian Huanga aDepartment of Chemistry, Hangzhou University, Hangzhou 310028, China bDepartment of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA A new method for the formation of 1,1- and (Z)-1,2-dialkylselenapenta-1,4-dienes by coupling allylation of dialkylselenaethenylboranes with allyl bromide in the presence of NaOMe and CuBr·SMe2 is described; the reaction proceeds via the migration of an alkylselenyl group from one olefinic carbon to another.Few syntheses of diselenaalkenes have been reported to date.1 However, there are still many classes of diselenaalkenes that cannot be synthesised generally, especially dialkylselenaalkenes.Here we report a new method for the synthesis of 1,1- and (Z)-1,2-dialkylselenapenta-1,4-dienes, which are obtained by the treatment of (Z)-1,2-dialkylselenaethenylboranes with allylic bromide in the presence of sodium methoxide and copper(I) bromide–methyl sulfide. The formation of the 1,1-dialkylselenapenta-1,4-dienes involves a rearrangement of the alkylselenyl group.We recently reported that the coupling reaction of alkylselenavinylcopper compounds, readily derived by the hydroboration of terminal2 or internal3 alkylselenaacetylenes with dialkylboranes followed by treatment with NaOMe and CuBr.SMe2, with organic halides provides the corresponding alkylselenaalkenes. In the present work, however, dialkylselenaethenylboranes 1, obtained from the hydroboration of dialkylselenaacetylenes with 9-borabicyclo[3.3.1]nonane (9-BBN), were treated successively with sodium methoxide and cuprous bromide–methyl sulfide, followed by coupling with allylic bromide.It was found that the coupling allylation proceeded smoothly under mild conditions and gave a mixture of the unexpected 1,1-dialkylselenapenta-1,4-dienes 2 and the corresponding (Z)-1,2-dialkylselenapenta-1,4-dienes 3 (Scheme 1). The results are presented in Table 1. The stereochemistry of the 1,1-isomer 2a was confirmed by a triplet of the coupling constant (J 7.2 Hz) of one olefinic proton with the methylene related to the same carbon in the double bond in 1H NMR spectrum (300 MHz) and by NOE experiments [irradiation of two allyl methylene protons (d 3.07), NOE (%)]: H (d 6.21, olefinic H) (3.7).Brown4 and co-workers previously reported that alkenylcopper intermediates, generated from alkenyldialkylborane derivatives of 9-borabicyclo[3.3.1]nonane, underwent coupling with allylic halides or 1-haloalk-1-ynes to provide stereodefined 1,4-dienes or conjugated enynes.We have also reported that heteroselenium-substituted alkenylboranes are transferred to the corresponding alkenylcoppers followed by coupling with organic halides to yield alkylselenaalkanes.2,3 These results showed that the reaction proceeded with retention of the alkenylborane configuration. It is not clear why the transformation of the dialkylselenaethenylboranes into the corresponding ethenylcoppers followed by coupling allylation produced the two isomers 2 and 3.In the present case, an additional consideration is that the possible mechanism according to which 1,1-dialkylselenapenta-1,4-dienes 2 were formed proceeds via trans-elimination of HSeR in the presence of base such as NaOMe because the RSe group sterically hinders the approach to boron (a precedent for such an elimination has been reported in the literature),5 followed by RSeH addition to the alkyne product in the opposite sense to yield (RSe)2CCH(BRp2) which would no longer be a hindrance to the attack at boron.The cupration and allylation could thus proceed to give 2 (Scheme 2). Experimental The 1H NMR spectra were recorded on an AZ-300 MHz with TMS as internal standard. Mass spectra were determined using a Finigan 8230 mass spectrometer. IR spectra were obtained in neat capillary cells on a Shimadzu IR-408 instrument. Elemental analyses were conducted using a Perkin-Elmer 240B elemental analyser.Silica gel 60 FC254 was used for analytical and preparative TLC. Silica gel columns were prepared using silica gel Q/BKUS 3–91 (100–200 mesh). The reactions were carried out in pre-dried glassware (150 °C, 4 h) and cooled under a stream of dry nitrogen. All solvents were dried, deoxygenated and redistilled before use. The dialkylselenaacetylenes7 were prepared according to literature methods. General Procedure for the Synthesis of Dialkylselenapenta- 1,4-dienes 2 and 3.·To a freshly prepared suspension of 9-borabicyclo[3.3.1]nonane (5 mmol) in THF (10 ml) at 0 °C was added dialkylselenaacetylene (5.1 mmol) in THF (2 ml) over 5 min.The reaction mixture was stirred until the precipitate completely disappeared (ca. 5 h). The solution was then poured into a suspen- *To receive any correspondence. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J.Chem. Research (M). Scheme 1 Scheme 2 Table 1 Yields and isomeric ratios obtained in the synthesis of 1,1- and (Z)-1,2-dialkylselenapenta-1,4-dienes 2a–g and 3a–g Isomeric ratioa Total yield Compound R (2:3) (%)b a bc def g Et Bu Me pentyl hexyl cyclohexyl Ph 1:3.3 1:1.8 1:8c 1:1.5 1:1.2 1:2.8 1:1.1c 82 81 83 79 80 73 75 aDetermined by 1H NMR. bIsolated yields based on dialkylselenaacetylenes employed. cFor compounds 3c and 3g, see ref. 6.J. CHEM.RESEARCH (S), 1997 289 sion of NaOMe (5.1 mmol) in THF (5 ml) at µ15 °C. After being stirred for 30 min, addition of this adduct to CuBr.SMe2 (1.05 g, 5.1 mmol) in THF (3 ml) at µ15 °C was followed, after 10 min, by the addition of 1.1 equiv. of allyl bromide. After further stirring at µ15 °C for 1.5 h, the reaction was allowed to warm slowly to room temperature. The product was then extracted into pentane, filtered and concentrated in vacuo. The residue was purified by flash chromatography on a 3 ftÅ1 inch column with light petroleum (bp 30–60 °C) as eluent to give 2 and 3. 1,1-Diethylselanapenta-1,4-diene 2a. Oil. Rf 0.66 (pentane). vmax/ cmµ1 1637, 819. dH 6.21 (1 H, t, J 7.2 Hz), 5.67 (1 H, m), 5.0 (2 H, m), 3.07 (2 H, dd, J 7.2, 7.5 Hz, 2.91 (2 H, q, J 7.9 Hz), 2.88 (2 H, q, J 7.8 Hz), 1.75 (3 H, t, J 7.9 Hz), 1.69 (3 H, t, J 7.8 Hz). m/z 284 (M+ +2, 13%), 255 (55), 225 (17), 145 (100) (Found: C, 38.77; H, 6.03. C9H16Se2 requires C, 38.31; H, 5.72%).(Z)-1,2-Diethylselenapenta-1,4-diene 3a. Oil. Rf 0.53 (pentane). vmax/cmµ1 1621, 798. dH 5.95 (1 H, s), 5.79 (1 H, m), 5.08 (2 H, m), 3.18 (2 H, d, J 7.59 Hz), 2.87 (2 H, q, J 7.9 Hz), 2.81 (2 H, q, J 7.7 Hz), 1.59–1.80 (6 H, m). m/z 284 (M+ +2, 17%), 255 (47), 225 (21), 145 (100) (Found: C, 37.91; H, 6.11. C9H16Se2 requires C, 38.31; H, 5.72%). 1,1-Dibutylselenapenta-1,4-diene 2b. Oil. Rf 0.69 (pentane). vmax/ cmµ1 1631, 808. dH 6.19 (1 H, t, J 7.2 Hz), 5.88 (1 H, m), 5.01 (2 H, m), 3.05 (2 H, dd, J 7.2, 7.54 Hz), 2.75–2.97 (4 H, m), 1.56–1.82 (4 H, m), 1.20–1.50 (4 H, m), 0.97 (3 H, t, J 6.7 Hz), 0.91 (3 H, t, J 6.7 Hz).m/z 340 (M+ 2, 9%), 283 (51), 226 (19), 145 (100) (Found: C, 46.52; H, 7.55. C13H24Se2 requires C, 46.16; H, 7.15%). (Z)-1,2-Dibutylselenapenta-1,4-diene 3b. Oil. Rf 0.51 (pentane). vmax/cmµ1 1619, 795. dH 5.97 (1 H, s), 5.81 (1 H, m), 514 (2 H, m), 3.20 (2 H, d, J 7.6 Hz), 2.74–2.97 (4 H, m), 1.57–1.79 (4 H, m), 1.24–1.53 (4 H, mn), 0.98 (3 H, t, J 6.9 Hz), 0.91 (3 H, t, J 6.8 Hz).m/z 340 (M+, 12%), 283 (43), 226 (22), 145 (100) (Found: C, 45.72; H, 6.89. C13H24Se2 requires C, 46.16; H, 7.15%). 1,1-Dimethylselenapenta-1,4-diene 2c. Oil. Rf 0.65 (pentane). vmax/ cmµ1 1630, 811. dH 6.11 (1 H, t, J 7.1 Hz), 5.72 (1 H, m), 5.03 (2 H, m), 3.07 (2 H, dd, J 7.1, 4 Hz), 2.22 (3 H, s), 2.17 (3 H, s). m/z 245 (M+ 2, 14%), 241 (21), 225 (57), 145 (100) (Found: C, 32.75; H, 4.47. C7H12Se2 requires C, 33.09; H, 7.76%). 1,1-Dipentylselenapenta-1,4-diene 2d. Oil. Rf 0.68 (pentane). vmax/ cmµ1 1641, 822. dH 6.18 (1 H, t, J 7.2 Hz), 5.78 (1 H, m), 5.03 (2 H, m), 3.02 (2 H, dd, J 7.2m, 7.6 Hz), 2.81 (2 H, q, J 7.8 Hz), 2.79 (2 H, t, J 8.1), 1.56–1.80 (4 H, m), 1.15–1.52 (8 H, m), 0.96 (3 H, t, J 6.9 Hz), 0.92 (3 H, t, J 6.8 Hz). m/z 368 (M+ +2, 13%), 313 (3), 297 (48), 225 (16), 191 (4), 163 (4), 145 (100) (Found: C, 49.64; H, 7.38. C15H28Se2 requires C, 49.18; H, 7.70%). (Z)-1,2-Dipentylselenapenta-1,4-diene 3d.Oil. Rf 0.55 (pentane). vmax/cmµ1 1623, 794. dH 5.98 (1 H, s), 5.76 (1 H, m), 5.05 (2 H, m), 3.12 (2 H, d, J 7.6 Hz), 2.75–2.91 (4 H, m), 1.53–1.78 (4 H, m), 1.15–1.48 (8 H, m), 0.93 (3 H, t, J 6.9 Hz), 0.88 (3 H, t, J 6.7 Hz). m/z 368 (M++2, 16%), 323 (3.6), 297 (60), 256 (5.6), 225 (18), 186 (8), 145 (100) (Found: C, 49.61; H, 7.96. C16H28Se2 requires C, 49.18; H, 7.70%). 1,1-Dihexylselenapenta-1,4-diene 2e. Oil. Rf 0.66 (pentane). vmax/ cmµ1 1645. 819. dH 6.19 (1 H, t, J 7.2 Hz), 5.77 (1 H, m), 5.05 (2 H, m), 3.07 (2 H, dd, J 7.2, 7.6 Hz), 2.75–2.92 (4 H, m), 1.55–1.677 (4 H, m), 1.17–1.47 (12 H, m), 0.90 (3 H, t, J 6.8 Hz), 0.88 (3 H, t, J 6.8 Hz). m/z 396 (M+ +2, 9%), 311 (41), 225 (5), 145 (100) (Found: C, 51.32; H, 7.79. C17H32Se2 requires C, 51.78 H, 8.18%). (Z)-1,2-Dihexylselenapenta-1,4-diene 3e. Oil. Rf 0.54 (pentane). vmax/cmµ1 1628, 798. dH 5.59 (1 H, s), 5.71 (1 H, m), 5.07 (2 H, m), 3.15 (2 H, d, J 7.7 Hz), 2.73–2.90 (4 H, m), 1.56–1.79 (4 H, m), 1.17–1.48 (12 H, m), 0.93 (3 H, t, J 6.8 Hz), 0.88 (3 H, t, J 6.7 Hz). m/z 396 (M+ +2, 9%), 311 (46), 225 (5), 145 (100) (Found: C, 52.22; H, 8.55. C17H32Se2 requires C, 51.78; H, 8.18%). 1,1-Dicyclohexylselenapenta-1,4-diene 2f. Oil. Rf 0.66 (pentane). vmax/cmµ1 1647, 824. dH 6.08 (1 H, t, J 7.1 Hz), 5.66 (1 H, m), 5.0 (2 H, m), 3.01 (2 H, dd, J 7.1, 7.5 Hz), 2.85–3.05 (2 H, br), 1.10–1.75 (20 H, m). m/z 392 (M+ +2, 14%), 309 (48), 225 (19), 145 (100) (Found: C, 52.77; H, 6.88.C17H28Se2 requires C, 52.31; H, 7.23%). (Z)-1,2-Dicyclohexylselenapenta-1,4-diene 3f. Oil. Rf 0.56 (pentane). vmax/cmµ1 1617, 792. dH 5.92 (1 H, s), 5.67 (1 H, m), 4.98 (2 H, m), 3.13 (2 H, d, J 7.6 Hz), 2.84–3.08 (2 H, br), 1.12–1.78 (20 H, m). m/z 392 (M+ +2, 15%), 309 (58), 225 (16), 145 (100) (Found: C, 51.94; H, 7.01. C17H28Se2 requires C, 51.31; H, 7.23%). 1,1-Diphenylselenapenta-1,4-diene 2g. Oil. Rf 0.59 (pentane). vmax/ cmµ1 1637, 1592, 1567, 815.dH 7.15–7.65 (10 H, m), 6.31 (1 H, t, J 7.0 Hz), 5.96 (1 H, m), 5.08 (2 H, m), 3.11 (2 H, dd, J 7.0, 7.4 Hz). m/z 380 (M+ +2, 11%), 379 (M+ +1, 10), 378 (M+, 9), 303 (55), 225 (20), 145 (100) (Found: C, 54.38; H, 4.61. C17H16Se2 requires C, 53.98; H, 4.26%). We thank the National Natural Science Foundation of China and the Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Academia Sinica, for financial support. Received, 28th January 1997; Accepted, 22nd April 1997 Paper E/7/00636E References 1 (a) B. T. Grobel and D. Seebach, Chem. Ber., 1977, 110, 85; (b) H. Kuniyasu, A. Ogawa, S. I. Miyazaki, I. Ryu, N. Kambe and N. Sonoda, J. Am. Chem. Soc., 1991, 113, 9796. 2 D. Y. Yang and X. Huang, Synth. Commun., 1996, 23, 4369. 3 D. Y. Yang and X. Huang, J. Chem. Res. (S), 1996, 470. 4 (a) J. B. Campbell and H. C. Brown, J. Org. Chem., 1980, 45, 550; (b) H. C. Brown and J. B. Campbell, J. Org. Chem., 1980, 45, 552; (c) H. C. Brown and G. A. Molander, J. Org. Chem., 1981, 46, 647. 5 (a) H. Bock, W. Ried and U. Stein, Chem. Ber., 1981, 114, 673; (b) A. L. Braga, J. V. Comasseto, N. Petragnani, Synthesis, 1984, 240; (c) H. J. Bestmann and H. Frey, Synthesis, 1984, 243. 6 D. Y. Yang and X. Huang, Tetrahedron Lett., in the press. 7 L. Brandsma, Recl. Trav. Chim. Pays-Bas, 1964, 83, 307.
ISSN:0308-2342
DOI:10.1039/a700636e
出版商:RSC
年代:1997
数据来源: RSC
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13. |
Monodechlorination of6,6-Dichloro-3-phosphabicyclo[3.1.0]hexane 3-Oxides by CatalyticHydrogenation† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 290-29
György Keglevich TiborNovák,
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摘要:
290 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 290–291† Monodechlorination of 6,6-Dichloro- 3-phosphabicyclo[3.1.0]hexane 3-Oxides by Catalytic Hydrogenation† Gy�orgy Keglevich,*,a Tibor Nov�ak,a Antal Tungler,a L�aszl�o Hegedu��s,a Áron Sz�ollo��sy,b Krisztina Lud�anyic and L�aszl�o To��kea aDepartment of Organic Chemical Technology, Technical University of Budapest, 1521 Budapest, Hungary bDepartment of General and Analytical Chemistry, Technical University of Budapest, 1521 Budapest, Hungary cCentral Chemical Research Institute for Hungarian Academy of Sciences, 1525 Budapest, Hungary Catalytic hydrogenation of the title compounds at ca. 88 °C and 9 bar in the presence of diethylamine led to a reasonable portion of monochlorocyclopropanes together with ca. 38% of hexahydrophosphinine oxides. There are only a few reports on the reductive monodechlorination of geminal dichlorocyclopropanes in the literature.1–4 We have recently found that the hydrogenation of dichlorophosphabicyclohexanes at ca. 88 °C and 9 bar in the presence of triethylamine afforded hexahydrophosphinines by reductive cyclopropane ring opening.5 Under the conditions applied, it was not possible to stop at the intermediate stages. Therefore we could not isolate and characterise the intermediates. Here we show how to perform the hydrogenations to yield a reasonable quantity of the monochloro species. It was not possible to achieve monodechlorination by carrying out the hydrogenations of the title compounds (e.g. 1a) at lower temperatures than 85–90 °C,5 as no reaction occurred below 85 °C. Hydrogenation of 1a at ca. 88 °C in the presence of diethylamine instead of triethylamine afforded, however, the monochloro species 2a(1) and 2a(2) in reasonable quantities. According to 31P NMR, the proportion of 2a(1) and 2a(2) was 40%, with the remainder being the fully dehalogenated cyclopropane 3 (20%) and the hexahydrophosphinine oxide 6a (40%) (Scheme 1, Table 1).A similar hydrogenation of the isopropoxy starting material consisting of 36% of 1b and 64% of 1pb gave the monochloro products as a mixture of four isomers [2b(1), 2b(2), 2pb(1) and 2pb(2)] in 64% yield, together with 36% of 6b (Scheme 1, Table 1). Our results are in accord with literature data showing that the outcome of the dehydrohalogenation may depend on the nature of the base employed.1 Partial or complete separation of the isomers 2a and 2pb was achieved by repeated column chromatography: isomer 2a(1) was isolated in a pure form, 2pb as a 61–39% mixture of isomers 2pb(1) and 2pb(2).The stereostructure of the starting material 1a is known from an earlier X-ray study6 and the structures of the isomers of the isopropoxy compound (1b and 1pb) were assigned on the basis of an analogy.7 As only the C-6 centre of the starting materials (1 and 1p) is involved in the hydrogenolysis, the relative configurations of the other asymmetric centres should remain unchanged.The distinction between isomer (1) and isomer (2) of 2 (and 2p) is possible on the basis of the stereospecific 3JHH couplings at C(6)·H. The X-ray structure6 of the starting material 1a served as a good basis for the estimation of the torsion angles in the two isomers. Hence, the H·C(5)·C(6)·H dihedral angle is ca. 147° for isomer (1) of 2 and 2p, and ca. 0° for isomer (2) of the same products, suggesting 3JHH couplings of 4.8 and 8.0 Hz, respectively.8 Isomer (1) and isomer (2) of the products (2 and 2p) were assigned on the basis of the measured couplings of ca. 3 and *To receive any correspondence (e-mail: keglevich@oct.bme.hu). †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Scheme 1 Table 1 Products from the hydrogenation of the phosphabicyclohexanes dP a (product composition in %)b Starting compound 2(1) 2(2) 2p(1) 2p(2) 3 Major 6 Minor 1a 71.8 80.0 73.2 37.0 (35.1)5 34.6 (33.0)5 (26) (14) (20) (29) (11) 1b+1pb 79.1c 82.8c 80.6 88.2 51.0 (50.5)5 49.9 (49.1)5 (15) (9) (15) (25) (28) (8) aIn CDCl3.bOn the basis of the 31P NMR intensities. cTentative assignments.J. CHEM. RESEARCH (S), 1997 291 7.3 Hz, respectively (Table 2). Isomers 2a(1), 2pb(1) and 2pb(2) were also characterised by 13C NMR (Table 3) and MS data. Interruption of the hydrogenation of 1a at an earlier stage resulted in a mixture containing 11% of 2a(1), 7% of 2a(2), 7% of 3, 23% of 6a and 6% of 1a according to 31P NMR.The remaining part at dP 30.7 (37%) and at dP 28.5 (9%) consisted of intermediate isomers. The major component was separated by column chromatography and assigned structure 5a by 13C NMR and MS. Thus, it was confirmed that the hydrogenation of 1 takes place through the tetrahydrophosphinine oxide 5, formed from the dihydrophosphine oxide 4.Experimental The same instruments were used as previously reported.5 The NMR spectra were recorded in CDCl3 solution. Coupling constants (J) are given in Hz. The starting materials 1a and 1b were prepared as described earlier.9,10 Hydrogenation of 1a. 6-Chloro-1-methyl-3-phenyl-3-phosphabicyclo[ 3.1.0]hexane 3-Oxide 2a(1) and 1-Methyl-3-phenyl-3- phosphabicyclo[3.1.0]hexane 3-Oxide 3.·A mixture of 1a (1.5 g, 5.46 mmol), Pd–C (0.9 g, 10%) and diethylamine (1.4 ml, 13.7 mmol) in methanol (50 ml) was hydrogenated at 85–90 °C and 9 bar until 1.8 equiv.of hydrogen was absorbed. Filtration and evaporation left an oil that was analysed by 31P NMR and GCMS (Table 1). Column chromatography (silica gel, 3% methanol in chloroform) afforded 0.21 g (16%) of 2a(1), 0.31 g (27%) of 6a and a fraction of 0.2 g consisting of ca. 50% of 3. 2a(1). dP 70.9; dH see Table 2 and 1.56 (s, 3 H, 1-Me), 1.65 (dd, 3JPH=21.9, 3JH(4)H=7.8, 1 H, 5-H), 2.29–2.44 [m, 3 H, C(2)·H2, C(4)·Ha], 2.63 [ddd, 3JHH=7.7, 2JPH=2JHH=18.3, 1 H, C(4)·Hb], 7.49–7.69 (m, 5 H, Ar); dC see Table 3; m/z (rel.int.) 240 (M+, 5), 225 (2), 205 (100), 125 (15), 77 (12), 91 (9); HRMS, M+ (Found: 240.0499. C12H14OPCl requires 240.0471 for the 35Cl isotope). 3. dP 72.3; m/z 206 (M+) (Found: M+ 206.0899. C12H15OP requires Mr 206.0861). 5-Methyl-1-phenyl-1,2,3,6-tetrahydrophosphinine 1-Oxide 5a.— Compound 5a was obtained by column chromatography (silica gel, 3% MeOH in CHCl3) after interrupting the above hydrogenation.Yield: 21%. dP 30.5; dC 22.1 (J=4.9, C-3), 23.8 (J=67.4, C-6), 25.7 (J=11.1, Me), 31.4 (J=66.2, C-2), 122.5 (J=12.6, C-4), 128.3 (J=11.5, C-2p),* 129.5 (J=9.3, C-3p),* 131.5 (C-4p), 132.5 (J=96.6, C-1p) (assignments marked * may be reversed); m/z (rel. int.) 206 (M+, 100), 191 (28), 125 (68), 91 (29), 77 (26). (Found: M+ 206.0895. C12H15OP requires Mr 206.0861). Hydrogenation of 1b and 1pb. 6-Chloro-1-methyl-3-isopropoxy- 3-phosphabicyclo[3.1.0]hexane 3-Oxides 2bp(1) and 2pb(2).·The mixture of isomers (1b and 1pb) was hydrogenated in isopropyl alcohol as described above for 1a.Column chromatography of the mixture (Table 1) led to 0.25 g (21%) of 2pb consisting of 61% or 2pb(1) and 39% of 2pb(2) and 0.30 g (30%) of 6b. For 2pb(1): dP 80.9. For 2pb(2): dP 88.4. For the mixture: dH, Table 2; dC, Table 3; CI–MS, m/z 223 (M+H); m/z (rel. int.) 222 (M+, 1), 207 (5), 187 (25), 180 (18), 145 (100).OTKA support of this work is acknowledged (grant. no.: T 014917). Received, 26th November 1996; Accepted, 29th April 1997 Paper E/6/08000F References 1 P. Rylander, in Catalytic Hydrogenation in Organic Synthesis, Academic Press, New York, 1979, pp. 235–236. 2 A. R. Pinder, Synthesis, 1980, 425. 3 K. Isogai and T. Kazama, J. Chem. Soc. Jpn., 1967, 88, 106 (Chem. Abstr., 1967, 67, 43 125). 4 K. Isogai, S. Kondo, K. Katsura, S. Sato, N. Yoshihara, Y. Kawamura and T. Kazama, J.Chem. Soc. Jpn., 1970, 91, 561 (Chem. Abstr., 1971, 74, 3186d). 5 Gy. Keglevich, A. Tungler, T. Nov�ak and L. To��ke, J. Chem. Res. (S), 1996, 528. 6 Gy. Keglevich, F. Janke, V. F�ul�op, A. K�alm�an, G. T�oth and L. To��ke, Phosphorus Sulfur Rev�acs, L. To��ke, K. � Ujsz�aszy, Gy. Argay, M. Czugler and A. K�alm�an, Heteratom. Chem., 1993, 4, 329. 8 E. Pretsch, J. Steibl, W. Simon and T. Clerc, Tables of Spectral Data for Structure Determination of Organic Compounds, Springer-Verlag, Berlin, H25, 1981. 9 Gy. Keglevich, I. Petneh�azy, P. Mikl�os, A. Alm�asy, G. T�oth, T. To��ke and L. D. Quin, J. Org. Chem., 1987, 52, 3983. 10 Gy. Keglevich, J. Brlik, F. Janke and L. To��ke, Heteroatom. Chem., 1990, 1, 419. Table 2 Partial 1H NMR data for the monochloro products dH a (multiplicity, J in Hz) 2a(1) 2pb(1) 2pb(2) C(6)—H 2.68 (d, 3JHH=2.9) 2.95 (d, 3JHH=3.0) 3.25 (dd, 3JHH=7.3, 4JPH=3.5b) aIn CDCl3. bConfirmed by 31P decoupled spectra. Table 3 13C NMR data for the monochlorophosphabicyclohexanes dC a (JPC in Hz) Compound C-1 C-2 C-4 C-5 C-6 C(1)—Me C-1p C-2p C-3p C-4p 2a(1) 2pb(1) 2pb(2) 28.4 (7.3) 24.9 (11.4) 22.5 (12.1) 38.1 (66.8) 34.2 (89.2) 28.8 (88.7) 32.2 (66.7) 28.8 (88.7) 23.6 (89.0) 30.8 (5.6) 27.8 (8.7) 23.7 (8.6) 45.1 (3.8) 44.3 (4.0) 45.8 (6.3) 19.2 (7.4) 19.2 (9.7) 21.5 (10.6) 132.5 (88.3) 130.2b (9.2) 70.1 (6.5) 69.3 (6.5) 129.0b (11.1) 24.1 (3.7) 24.4 (3.6) 132.2 (2.1
ISSN:0308-2342
DOI:10.1039/a608000f
出版商:RSC
年代:1997
数据来源: RSC
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14. |
Nickel Catalysed Oligomerisation of Ethylene andCopolymerisation of Ethylene with CarbonMonoxide†,‡ |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 292-293
Robert Brüll,
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摘要:
P Ni O R1 R2 Ph Ph Ph L chelate part organo part R1 = H, Ph, SO3Na R2 = OMe, Ph L = PEt3, PPh3, pyridine SH SH SH SH 1 2 SH SH Me SH SH Me SH SH Et SH SH Me 3 4 5 6 20 15 10 10 14 18 22 26 30 34 5 0 Cn m(p)in % E/7/01419H/4 experimental theoretical 292 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 292–293† Nickel Catalysed Oligomerisation of Ethylene and Copolymerisation of Ethylene with Carbon Monoxide†,‡ Robert Br�ulla and Wilhelm Keim*b aDepartment of Chemistry and Biochemistry, Rand Afrikaans University, PO Box 524, Auckland Park, Johannesburg 2006, South Africa bInstitut f�ur Technische Chemie und Petrolchemie der RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany Ethylene is oligomerised and ethylene and carbon monoxide copolymerised by in situ nickel catalysts and aromatic sulfanyl ligands.Polyketone, the copolymerisation product of ethylene and carbon monoxide, is of high industrial interest as the copolymer can easily be functionalised, it displays excellent physical and mechanical properties and is photodegradable.These aspects have been extensively reviewed in several papers.2–8 The palladium catalysed synthesis, developed by Shell, reached the stage of industrial production in 1995.9 Nickel provides an economic alternative as it is active for oligomerisation of olefins as well as for carbonylation. The role of the chelating ligands in the olefin oligomerisation has been thoroughly investigated by Keim.10 While the chelate part influences activity and selectivity the function of the organo part is to generate the active species and tune the selectivity.10 P^O- and N^O-chelating systems turned out to produce only block copolymers in the ethylene/CO-copolymerisation. 11 In situ catalyst systems of Ni(cod)2 and sulfanylcarboxylic acids which function as S^O-ligands have been patented by Keim et al.12 Here we describe the utilisation of various disulfanyl compounds in the same capacity, some of them functioning as monodentate and others as potentially bidentate ligands.The strongly chelating dithiols 1 and 2 did not catalyse the copolymerisation of ethylene/CO. The non-chelating thiols 3–6, in contrast, led to the formation of polyketone as well as oligomers and polymers of ethylene (Tables 1–3). Mixtures of oligomers and polyethylene were formed with ethylene, their ratio depending on the conditions employed. The homopolymer displayed a bimodal molecular weight distribution, as was confirmed by GPC analysis.GC analysis of the oligomers revealed considerable deviation from the expected Schultz–Flory distribution. This is caused by incorporation of the primarily formed products into the reaction (Fig. 2). A perfectly alternating copolymer was obtained within a wide ethylene/CO ratio. Only traces of hexenes were obtained as by-products (Table 3). Even ligand 6, with the sulfanyl groups in the 1,4-positions, gave considerable yields of polyketone.The material was characterised by infrared spectroscopy, melting point and elemental analysis. Infrared *To receive any correspondence. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). ‡Dedicated to Professor em. Dr. techn. Dipl. Ing. Dr. phil. habil. Friedrich Asinger on the occasion of his 90th birthday.Fig. 1 Generalised catalyst precursor Fig. 2 Theoretical and experimental Schultz–Flory distribution of the ethylene oligomers produced with Ni(cod)2/3 Table 1 Oligomerisation of ethylene with Ni(cod)2 and 3 or 6 Experimenta Ligand Turnover number 12 36 698 1494 aReaction conditions: 0.22 mmol ligand+0.22 mmol Ni(cod)2 in 20 ml toluene, pethylene=40 bar, T=60 °C, t=12 h. Table 2 Oligomerisation with Ni(cod)2/3. Dependence of linearity and portion of 1-olefin of the C10- and C12-fraction on the temperature T/°Ca 30 60 100 140 Linearity (C10) (%) Portion of 1-olefin (C10) (%) Linearity (12) (%) Portion of 1-olefin (C12) (%) 60.3 15.9 51.6 24.4 66.6 22.2 61.1 30.6 56.4 14.4 47.4 23.9 53.7 11.9 42.4 21.9 aReaction conditions: 0.22 mmol 3+0.22 mmol Ni(cod)2 in 20 ml toluene, Pethylene=40 bar, T=60 °C, t=12 h.SH SH + Ni(cod)2 S S Ni + cod + cyclooctene (1) 7 1 (s) HS SH + 2 Ni(cod)2 S S Ni Ni –2 cod S S Ni H Ni H –2 cod 8 9 i, ii, + CO i, a-olefins ii, polyketone (3) (2) 6 J.CHEM. RESEARCH (S), 1997 293 spectroscopy and elemental analysis showed that the polyketone was perfectly alternating.13 According to solid state 13C NMR, unbranched material was produced. Unsaturated end groups could not be detected. Steric crowding of the phenyl ring results in lower conversions (ligands 4 and 5). Monothiols containing electron withdrawing substituents on the phenyl ring, like 3-chlorobenzenethiol or pentafluorobenzenethiol, also showed some activity in the copolymerisation, although the rates of conversion were much smaller (turnover number 15 or 47, respectively) than with 3–6.The reaction was unsuccessful when aliphatic dithiols like 1,2-disulfanylethane or 1,3-disulfanylpropane were used. Aromatic solvents turned out to be the most suitable (Table 4). Ni(cod)2 was also replaced by other nickel salts containing a Br�onsted base like acetate or acetylacetonate. The conversions were generally lower than with Ni(cod)2 without change in the selectivity.The deactivating function of ligands 1 and 2 can be explained by the formation of nickel complexes like 7 which precipitate from the solution [eqn. (1)]. The oxidative addition of compounds with acidic hydrogen atoms to Ni(cod)2 is well known as a key step in the formation of catalyst precursors.10 In the case of 6 this could also be observed by the disappearance of the sulfanyl resonance in the 1H NMR spectrum. Based on this observation a hypothetical mechanism according to eqns.(2) and (3) can be proposed for the non-chelating ligands 3–6. The mechanistic scheme accommodates the striking difference in activity between mono- and non-chelating-bisbenzenethiols by showing the formation of a binuclear hydride 9 which is not possible with monothiols. The hydride 9 could not be detected by 1H NMR or infrared spectroscopy. Attempts to isolate the precursor, complex 8, or the hydride 9 from the catalyst solution were unsuccessful.Experimental All experiments were carried out under argon. General Procedure for the Preparation of the Catalyst Solutions and the Copolymerisation.·The ligand and Ni(cod)2 were separately dissolved at µ20 °C in 10 ml of solvent. The ligand was added to the organometallic component and then the solution was allowed to warm to room temperature when it turned brown. The catalyst solution was transferred by a syringe and a Teflon cannula into an autoclave which was then pressurised with ethylene and carbon monoxide and placed in an oil bath.The turnover numbers are calculated as molproducts/(molcatalystÅ12 h). We thank British Petroleum, London, for financial support and assistance in analytical problems. Received, 28th February 1997; Accepted, 29th April 1997 Paper E/7/01419H References 1 Results based on R. Br�ull, PhD thesis, RWTH Aachen, 1995. 2 A. Sen, Adv. Polym. Sci., 1986, 73/74, 125. 2 P. K. Wong (Shell), Eur.Pat. Appl., 1989, 324 998. 4 J.-T. Chen, Y.-S. Yeh and A. Sen, J. Chem. Soc., Chem. Commun., 1989, 965. 5 W. P. Gergen, R. G. Lutz and E. R. George (Shell), Eur. Pat. Appl., 1989, 345 854. 6 A. X. Zhao and J. C. W. Chien, J. Polym. Sci., Part A, Polym. Chem., 1992, 30, 2735. 7 S. K. L. Li and J. E. Guillet, J. Polym. Sci., Part A, Polym. Chem., 1980, 18, 2221 and references cited therein. 8 F. Y. Xu and J. C. W. Chien, Macromolecules, 1993, 26, 3485. 9 E. Drent, J. A. M. van Broekhoven and P. H. M. Budzelaar, in Applied Homogeneous Catalysis with Organometallic Compounds, ed. B. Cornils and W. A. Herrmann, VCH, Weinheim, 1996, p. 333 and references cited therein. 10 W. Keim, New J. Chem., 1994, 18, 93. 11 R. D. Beckers, PhD thesis, Aachen, 1991. 12 B. Driessen, M. J. Green and w. Keim, Eur. Pat. Appl., 1992, 407 759 (Chem. Abstr., 1992, 1163). 13 O. Hummel, Atlas der Kunststoffanalyse, Band 1, 1. Teil, Carl Hanser Verlag, M�unchen, 1968, pp. 127 and 176. Table 3 Ethylene/CO-copolymerisation with Ni(cod)2 and non-chelating dithiols 3–6 Experimenta Ligand Turnover number 3456 3456 287 165 149 113 aReaction conditions: 0.22 mmol ligand+0.22 mmol Ni(cod)2 in 20 ml toluene, pethylene=10 bar, pCO=5 bar, T=60 °C, t=12 h. Table 4 Influence of solvent on the copolymerisation with Ni(cod)2/3 Experimenta Solvent Turnover number 789 10 11 methanol dichloromethane cyclohexane mesitylene toluene 5 32 61 203 287 aReaction conditions: 0.22 mmol Ni(cod)2+0.22 mmol 3 in 20 ml toluene, pethylene=30 bar, pCO=10 bar, T=60 °C, t=12
ISSN:0308-2342
DOI:10.1039/a701419h
出版商:RSC
年代:1997
数据来源: RSC
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15. |
Synthesis of 4,4′-(1,4-Phenylene)di-pyridine and-pyrimidine Derivatives† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 294-295
Rafat Mohamed Shaker,
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摘要:
CHO CHO CH2 + 2 CN CN O het Me + 2 1 2 3a–e CH CH C(CN)2 C(CN)2 CH CH CHCO CHCO het het 5a,b,d 4 MeCO2NH4 N N het CN het NC NH3–H2 NH2 H2N 2-thienyl 2-furyl 5-methyl-2-furyl 2-pyridyl 3-pyridyl 3,5,6,7 het a bc de CN OH OH CN het CN het CN 6 +3 +2 7 294 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 294–295† Synthesis of 4,4p-(1,4-Phenylene)di-pyridine and -pyrimidine Derivatives† Rafat Mohamed Shaker* and Fathy Fahim Abdel-Latif Chemistry Department, Faculty of Science, El-Minia University, 61519, El-Minia, A.R.Egypt The preparation and structural characterization of 4,4p-(1,4-phenylene)di-pyridine and -pyrimidine derivatives are described. The biological importance of a variety of pyridine and pyrimidine derivatives has resulted in a lot of interest in their syntheses.1–5 As a part of our program directed towards the synthesis of heterocyclic derivatives with possible biological activity,6–11 the present work is aimed at synthesizing 4,4p-(1,4-phenylene)di-pyridine and -pyrimidine derivatives in high yields by a one-pot method from basic laboratory reagents.Thus, reacting a mixture of benzene-1,4-dicarbaldehyde (1), malononitrile (2) and 2-acetylthiophene (3a) in ethanol containing a catalytic amount of ammonium acetate (1:2.2) under reflux for 3 h afforded 4,4p-(1,4-phenylene)di[2- amino-3-cyano-6-(2-thienyl)pyridine] (7a) (see Scheme 1). The structure of 7a was established by analytical and spectral data (see Experimental).The formation of 7a was rationalized in terms of the initial formation of 4 or 5a followed by the addition of 3 or 2 to the ylidenic bond forming an acyclic intermediate 6. Amination of 6 in the presence of ammonium acetate12 followed by cyclization of the enamine and partial dehydrogenation under the reaction conditions afforded the final product (see Scheme 1). Structural proof was obtained through a two-component condensation of 2,2p-(1,4-phenylene)di(1,1-dicyanoethylene) (4)13 and/or 5a14,15 with 3a or 2 (1:2) under the previous conditions.Compound 7a was also afforded (see Experimental). Compounds 7b–e were prepared in similar way (see Scheme 1). We extended the previous reaction to a wide range of active methylene carbonyl reagents. Thus, treatment of 1 with 2 and cycloalkanones 8a–c under the reaction conditions mentioned above afforded 9a–c (see Scheme 2). Meanwhile, the ternary condensation of 1, 2 and cyclohexanone (8b) in refluxing alcoholic sodium ethoxide gave 4 , 4 p- ( 1 , 4 - p h e n y l e n e ) d i [ 3 - c y a n o - 2 - e t h o x y - 5 , 6 , 7 , 8 - t e t r a h y d r o - quinoline] (10) (see Scheme 2).Alternatively, compounds 9a–c and 10 could also be prepared by treating 4 with cycloalkanones 8a–c under the same reaction conditions (see Scheme 2). The structures of 9a–c and 10 were confirmed by analytical and spectral data (see Experimental). To extend the scope of this reaction to the synthesis of pyrimidine derivatives, we studied another model system that contained thiourea and/or urea.Thus, treatment of 1 with 11a,b and thiourea (12a) or urea (12b) (1:2.2) in ethanol containing catalytic amounts of hydrochloric acid yielded the corresponding 4,4p-(1,4-phenylene)di(1,2,3,4-tetrahydropyrimidines) 13a–c. The structure of 13 was deduced on the basis of analytical and spectral data (see Scheme 3 and Experimental). Experimental All melting points are uncorrected.IR spectra were recorded (KBr) on a Shimadzu 480 spectrophotometer. 1H NMR Spectra were recorded in [2H6]Me2SO on Varian EM-390 and Varian XL 200 (90 and 200 MHz) spectrometers with Me4Si as internal standard; chemical shifts d expressed in ppm. Mass spectra were recorded on a Finnigan MAT 8430 mass spectrometer. Analytical data were obtained from the Microanalytical Data Unit at Cairo University. Compounds 4 and 5 were prepared by literature procedures. 13–16 General Procedure for the Synthesis of Compounds 7 and 9.Method A.·A mixture of 1 (0.01 mol), 2 (0.02 mol), ammonium acetate (0.08 mol) and the appropriate ketone (0.02 mol) of either 3a–e or 8a–e in absolute ethanol (50 ml) was heated under reflux for 3 h. The solid product formed was collected by filtration and recrystallized from the appropriate solvent. Method B.·A mixture of 4 (0.01 mol), ammonium acetate (0.08 mol) and the appropriate ketone (0.02 mol) of either 3a,c,e or 8a–c in absolute ethanol (50 ml) was heated under reflux for 3 h.The solid product formed was collected and purified as in method A. Alternative Synthesis of 7a,b,d.·A solution of 5a,b,d (0.01 mol), ammonium acetate (0.08 mol) and 2 (0.02 mol) in absolute ethanol (50 ml) was heated under reflux for 3 h. The solid product was collected by filtration and recrystallized from the appropriate solvent. 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i [ 2 - a m i n o - 3 - c y a n o - 6 - ( 2 - t h i e n y l )p y r i d i n e ] (7a).·Obtained in 76% yield, mp a300 °C (from DMF); (Found: C, 65.4; H, 3.3; N, 17.5; S, 13.3.C26H16N6S2 requires C, 65.54; H, 3.38; N, 17.63; S, 13.43%); vmax/cmµ1 3400, 3300 (NH2) and 2210 (CN). dH 6.2 (s, 4 H, 2 NH2), 7.2 (m, 2 H, 2 thiophene 4-H), 7.3 (d, J 6.0 Hz, 2 H, 2 thiophene 3-H), 7.4 (d, J 6.0 Hz, 2 H, 2, thiophene 5-H), 7.6–7.8 (m, 4 H, Ar-H), 8.1 (s, 2 H, 2 pyridyl 5-H). 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i [ 2 - a m i n o - 3 - c y a n o - 6 - ( 2 - f u r y l ) p y r i d i n e ] (7b).·Obtained in 71% yield; mp a300 °C (from DMF); (Found: C, 70.3; H, 3.5; N, 19.0.C26H16N6O2 requires C, 70.26; H, 3.62; N, 18.91%); vmax/cmµ1 3400, 3200 (NH2) and 2200 (CN). dH 6.3 (s, 4 H, 2 NH2), 6.5–7.5 (m, 6 H, 2 furan protons), 7.6–7.8 (m, 4 H, Ar-H) and 8.0 (s, 2 H, 2 pyridyl 5-H). *To receive any correspondence. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J.Chem. Research (M). Scheme 1O a n = 6 b n = 5 c n = 4 [CH2] n 8 n = 5 MeCO2NH4 EtONa N N CN CN NH2 NH2 N N CN CN OEt OEt [CH2] n–1 10 a n = 6 b n = 5 c n = 4 9 4 +8b EtONa + 8a–c MeCO2NH4 1 + 2 + 1:2:2 [CH2] n–1 CH2 + 2 COR COMe X H2N NH2 + 2 1 a X = S b X = O 12 N N N N X X Me COR ROC Me a R = Ph b R = Me 11 a R = Ph, X = S b R = Me, X = S c R = Ph, X = O 13 EtOH, H+ H H H H J. CHEM. RESEARCH (S), 1997 295 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i [ 2 - a m i n o - 3 - c y a n o - 6 - ( 5 - m e t h y l - 2 - f u r y l ) p y r i - dine] (7c).·Obtained in 75% yield; mp a300 °C (from DMF); (Found: C, 71.3; H, 4.2; N, 17.8.C28H20N6O2 requires C, 71.17; H, 4.26; N, 17.78%); vmax/cmµ1 3400, 3200 (NH2) and 2200 (CN). dH 2.1 (s, 6 H, 2 CH3), 6.2 (s, 4 H, 2 NH2), 6.5 (d, J 3.5 Hz, 2 H, 2 furan 4-H), 7.5 (d, J 3.5 Hz, 2 H, 2 furan 3-H), 7.6–7.8 (m, 4 H, Ar-H), 8.0 (s, 2 H, 2 pyridyl 5-H). 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i [ 2 - a m i n o - 3 - c y a n o - 6 - ( 2 - p y r i d y l )p y r i d i n e ] (7d).·Obtained in 68% yield; mp a300 °C (from DMF); (Found: C, 72.0; H, 3.7; N, 24.2. C28H18N8 requires C, 72.09; H, 3.88; N, 24.02%); vmax/cmµ1 3400, 3200 (NH2) and 2200 (CN). dH 6.3 (s, 4 H, 2 NH2), 7.6–7.8 (m, 4 H, Ar-H) and 8.1–8.4 (m, 10 H, pyridyl H). 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i [ 2 - a m i n o - 3 - c y a n o - 6 - ( 3 - p y r i d y l )p y r i d i n e ] (7e).·Obtained in 74% yield; mp a300 °C (from DMF); (Found: C, 72.1; H, 3.9; N, 23.9.C18H18N8 requires C, 72.09; H, 3.88; N, 24.02%); vmax/cmµ1 3400, 3200 (NH2) and 2200 (CN). 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i ( 2 - a m i n o - 3 - c y a n o - 6 , 7 , 8 , 9 - t e t r a h y d r o - 5 H - cyclohepta[b]pyridine) (9a).·Obtained in 81% yield; mp a300 °C (from DMF–EtOH); (Found: C, 74.8; H, 6.3; N, 18.8. C28H28N6 requires C, 74.97; H, 6.29; N, 18.73%); vmax/cmµ1 3400, 3300 (NH2) and 2200 (CH).dH 1.1–3.0 (m, 20 H, 2 [CH2]5), 6.5 (s, br, 4 H, 2 NH2), 7.3–7.6 (m, 4 H, Ar-H); m/z 449 (M+ +1, 100%). 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i ( 2 -a m i n o - 3 - c y a n o - 5 , 6 , 7 , 8 - t e t r a h y d r o q u i n o - line) (9b).·Obtained in 86% yield; mp a300 °C (from DMF– EtOH); (Found: C, 74.1; H, 54.7; N, 20.1. C26H24N6 requires C, 74.26; H, 5.75; N, 19.98%); vmax/cmµ1 3400, 3300 (NH2) and 2200 (CN). dH 1.3–3.2 (m, 16 H, 2 [CH2]4), 6.4 (s, 4 H, 2 NH2) and 7.2–7.5 (m, 4 H, Ar-H). 4 , 4 p- ( 1 , 4 - P h e n y l e n e ) d i ( 2 - a m i n o - 3 - c y a n o - 6 , 7 - d i h y d r o - 5 H - c y c l o - penta[b]pyridine) (9c).·Obtained in 73% yield; mp a300 °C (from DMF–EtOH); (Found: C, 73.5; H, 5.2; N, 21.2. C24H20N6 requires C, 73.45; H, 5.13; N, 21.41%); vmax/cmµ1 3400, 3300 (NH2) and 2200 (CN). dH 1.5–2.2 (m, 12 H, 2 [CH2]3), 6.4 (s, 4 H, 2 NH2) and 7.3–7.5 (m, 4 H, Ar-H). Synthesis of 4,4p-(1,4-Phenylene)di(3-cyano-2-ethoxy-5,6,7,8-tetrahydroquinoline) (10).Method A.·A solution of sodium (0.02 mol) in absolute ethanol (30 ml), was added to a stirred solution of 1 (0.01 mol), 2 (0.02 mol) and 8b (0.02 mol) in absolute ethanol (20 ml). The resulting solution was refluxed for 2 h and then, after cooling to room temperature, the precipitate was separated and collected by filtration, washed with ethanol and recrystallized from DMF–EtOH. Method B.·Sodium (0.02 mol) was dissolved in absolute ethanol (30 ml), and 8b (0.02 mol) was added.The mixture was stirred for 15 min and then added to a stirred suspension of 4 (0.01 mol) in absolute ethanol (20 ml). The resulting mixture was then refluxed for 2 h. The resulting product was worked-up as described for method A. Compound 10 was obtained in 80% yield; mp a300 °C; (Found: C, 75.1; H, 6.5; N, 11.8. C30H30N4O2 requires C, 75.29; H, 6.32; N, 11.7%); vmax/cmµ1 2220 (CN). dH 1.05 (t, 6 H, 2 OEt), 1.2–2.8 (m, 16 H, 2 [CH2]4), 4.1 (q, 4 H, 2 OEt) and 7.3 (s, 4 H, Ar-H).General Procedure for the Synthesis of Pyrimidine Derivatives 13a–c.·A mixture of 1 (0.01 mol), 11a,b (0.02 mol) and 12a,b (0.02 mol) in absolute ethanol (50 ml) containing 10 drops of concentrated hydrochloric acid was refluxed for 5 h. The solid product formed was collected by filtration and recrystallized from the appropriate solvent. 4,4p(1 , 4 - Phenylene)di(5 - benzoyl- 6 - methyl- 2 - thioxo- 1 , 2 , 3 , 4 - tetra - hydropyrimidine) (13a).·Obtained in 88% yield; mp 231–233 °C (from DMF–EtOH); (Found: C, 66.8; H, 4.9; N, 10.3; S, 11.9.C30H26N4O2S2 requires C, 66.90; H, 4.86; N, 10.40; S, 11.88%); vmax/ cmµ1 3400 (NH) and 1660 (CO). dH 1.72 (s, 6 H, 2 CH3), 5.25 (d, J 4.6 Hz, 2 H, 2 H-4), 7.16 (s, 4 H, Ar-H), 7.48 (m, 10 H, Ar-H), 9.68 (s, 2 H, 2 NH), 10.35 (d, J 4.6 Hz, 2 H, 2 NH). m/z 538 (M+, 8%). 4 , 4p- (1 , 4 - Phenylene)di(5 - acetyl- 6 - methyl- 2 - thioxo- 1 , 3 , 4 , 5 - tetra - hydropyrimidine) (13b).·Obtained in 78% yield; mp a300 °C (from DMF–EtOH); (Found: C, 58.1; H, 5.4; N, 13.4; S, 15.5.C20H22N4O2S2 requires C, 57.96; H, 5.35; N, 13.52; S, 15.44%); vmax/ cmµ1 3400 (NH) and 1660 (CO). 4 , 4 p- ( 1 , 4 - Phenylene)di(5 - benzoyl- 6 - methyl- 2 - oxo- 1 , 2 , 3 , 4 - tetra - hydropyrimidine) (13c).·Obtained in 71% yield; mp a300 °C (from DMF–etOH); (Found: C, 71.2; H, 5.3; N, 11.2. C30H26N4O4 requires C, 71.13; H, 5.17; N, 11.06%); vmax/cmµ1 3400 (NH), 1660 and 1640 (CO).dH 1.7 (s, 6 H, 2 CH3), 5.3 (d, J 3 Hz, 2 H, 2 H-4), 7.3 (s, 4 H, Ar-H), 7.6 (m, 10 H, Ar-H), 9.7 (s, 2 H, 2 NH) and 10.3 (d, J 3 Hz, 2 H, 2 NH). Received, 23rd January 1997; Accepted, 29th April 1997 Paper E/7/00538E References 1 J. L. Soto, C. Seoane, P. Zamorano and F. J. Cuadrado, Synthesis, 1981, 529. 2 J. S. Kwiatkowski and B. Pullman, Adv. Heterocycl. Chem., 1975, 18, 199. 3 Co Sankyo and Ube Industries, Jpn. Pat., 5936,667 (8436,667) (Chem. Abstr., 1984, 101, 1 109 392). 4 C. C. Cheng, Prog. Med. Chem., 1969, 6, 67 5 D. B. McNair Scott, T. L. V. Ulbricht, M. L. Rogers, E. Chu and C. Rose, Cancer Rev., 1959, 19, 15. 6 F. F. Abdel-Latif and R. M. Shaker, Bull. Soc. Chim. Fr., 1991, 127, 87. 7 F. F. Abdel-Latif and R. M. Shaker, Phosphorus Sulfur Silicon Relat. Elem., 1990, 48, 217. 8 F. F. Abdel-Latif, R. M. Shaker, S. A. Mahgoub and M. Z. A. Badr, J. Heterocyclic Chem., 1989, 26, 769. 9 F. F. Abdel-Latif, M. M. Mashaly, R. Mekheimer and T. B. Abdel-Alleem, Z. Naturforsch., B: Chem. Sci., 1993, 48, 817. 10 R. M. Shaker, Pharmazie, 1996, 148. 11 F. F. Abdel-Latif and R. M. Shaker, J. Chem. Res. (S), 1995, 146. 12 K. Saito, S. Kambe, A. Sakurai and H. Midorikawa, Synthesis, 1981, 211. 13 G. Manecke and D. Woehrle, Makromol. Chem., 1967, 102, 1 (Chem. Abstr., 1967, 67, 64829t). 14 Z. A. Ariyan and B. Mooney, J. Chem. Soc., 1962, 1519. 15 L. Greiner-Bechert and H. H. Otto, Arch. Pharm., 1996, 324, 563. 16 A. I. Baba, W. Wang, W. Y. Kim, L. Strong and R. H. Schmehl, Synth. Commun., 1994, 24, 1029. Scheme 2 Scheme 3
ISSN:0308-2342
DOI:10.1039/a700538e
出版商:RSC
年代:1997
数据来源: RSC
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16. |
Synthesis of Coumarins by Flash Vacuum Pyrolysis of3-(2-Hydroxyaryl)propenoic Esters,1 |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 296-297
Gary A. Cartwright,
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摘要:
R3 CHO OH Ph3P CO2R1 R2 R3 OH CO2R1 R2 R3 O O R2 + 1 2 R3 OH CO2R1 R2 R3 O O R2 3 R1 = Me, R2 = H, R3 = H 4 R1 = Me, R2 = H, R3 = Cl 5 R1 = Me, R2 = H, R3 = NO2 6 R1 = Et, R2 = Me, R3 = H 7 R1 = Et, R2 = Me, R3 = Cl 9 R2 = H, R3 = H 10 R2 = H, R3 = Cl 11 R2 = H, R3 = NO2 12 R2 = Me, R3 = H 13 R2 = Me, R3 = Cl OH H CO2Me 8 O 14 O R3 OH CO2R1 R2 R3 O R2 OR1 O H R3 O R2 • O O R3 R2 O FVP –R1OH 296 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 296–297† Synthesis of Coumarins by Flash Vacuum Pyrolysis of 3-(2-Hydroxyaryl)propenoic Esters†,1 Gary A.Cartwright and Hamish McNab* Department of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK Flash vacuum pyrolysis of 3-(2-hydroxyaryl)propenoic esters gives coumarins (and other fused a-pyrones) in high yield. The preparation of coumarins and other fused a-pyrones by tandem Wittig olefination–cyclisation processes from 3-(2-hydroxyaryl)propenoic esters has been a popular synthetic route to such ring systems since it was first exploited by Mali and Yadav in 1977 (Scheme 1).2,3 Cyclisation may take place directly under the olefination conditions, particularly when substantial amounts of Z alkenes are obtained, but there are often problems with the cyclisation of E alkenes which are normally the major products from the Wittig reactions of stabilised ylides.These problems have been addressed either by heating the substrate neat,2,4 or in situ in an inert solvent,2,3 or in diethylaniline,5 or alternatively by photochemical isomerisation,6,7 but all of these methods suffer from disadvantages of variable yields and conditions, or inconvenient work-up, or both.We now show that the cyclisation takes place consistently in high yield when the isolated 3-(2-hydroxyaryl)propenoic esters are subjected to flash vacuum pyrolysis (FVP). The Wittig reactions of the appropriate aldehyde 1 with the phosphoranes 2 (R1=Me, R2=H and R1=Et, R2=Me) take place under very mild conditions (room temperature, dry dichloromethane, 2 h), to give the alkenes 3–8 in 75–88% yields after dry flash chromatography on silica to remove triphenylphosphine oxide.From the magnitude of the vicinal coupling constants in their 1H NMR spectra, the product in most cases is predominantly the E isomer contaminated with only a trace of the Z isomer, and such materials have been found to be difficult to cyclise to the corresponding coumarin by traditional methods.The alkenes 3–8 were therefore subjected to FVP at a furnace temperature of 750 °C. Under these conditions, E and Z alkenes are known8 to equilibrate, and the latter are able to eliminate the appropriate alcohol in a concerted process. The resulting ketene intermediates then undergo electrocyclisation to the corresponding coumarin 9–13 or fused pyrone 14 which condenses at the exit point of the furnace (Scheme 2). From a practical stand-point, there are a number of advantages of this cyclisation method.First, the yields are consistently high (75–96%), and the conditions are suffi- ciently mild to be compatible with a range of substituents on both the alkene and the benzene ring. The work-up is simple, consisting only of scraping the product from the trap or dissolving it out in an appropriate solvent. No significant by-products are obtained. Finally, the ester precursors are conveniently volatile and suffer little or no decomposition in the inlet of the FVP apparatus, so the method is capable of being scaled up to multi-gram quantities.Experimental 1H and 13C NMR spectra were recorded at 200 and 50 MHz respectively for solutions in [2H6]DMSO unless otherwise stated. Coupling constants (J) are quoted in Hz. Methyl 3-Arylpropenoates.2·The appropriate aldehyde 1 (4 mmol) was dissolved in dry dichloromethane (50 ml), and methyl (triphenylphosphoranylidene)acetate 2 (R2=H) (1.337 g, 4 mmol) was added with continuous stirring.After 2 h the solvent was removed in vacuo and the crude material was subjected to dry flash chromatography on silica to remove the triphenylphosphine oxide. The material isolated was pure enough for further use. The following compounds were made using this procedure: Salicylaldehyde gave methyl 3-(2-hydroxyphenyl)propenoate 3 (0.62 g, 88%), mp 136–137 °C (from ethanol); (Found: C, 67.4; H, 5.6. C10H10O3 requires C, 67.35; H, 5.65%); dH 7.87 (1 H, d, 3J 16.0), 7.58 (1 H, m), 7.23 (1 H, m), 6.91 (1 H, m), 6.86 (1 H, m), 6.60 (1 H, d, 3J 16.0) and 3.70 (3 H, s); dC 167.09 (q), 140.40, 131.88 (q), 131.63, 128.72, 120.56 (q), 119.05, 116.71, 116.05 and 51.20; m/z 178 (M+, 31), 146 (100), 118 (82), 103 (25), 91 (34), 65 (10) and 32 (14). 2-Hydroxy-5-chlorobenzaldehyde gave methyl 3-(2-hydroxy-5- chlorophenyl)propenoate 4 (0.68 g, 80%), mp 145–147 °C (from *To receive any correspondence. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J.Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Scheme 1 Scheme 2J. CHEM. RESEARCH (S), 1997 297 ethanol); (Found: C, 56.1; H, 3.3. C10H9ClO3 requires C, 56.4; H, 3.3%); dH 7.79 (1 H, d, 3J 16.0), 7.67 (1 H, d, 4J 2.5), 7.24 (1 H, dd, 3J 8.7 and 4J 2.5), 6.91 (1 H, d, 3J 8.7), 6.67 (1 H, d, 3J 16.0) and 3.48 (3 H, s); dC 116.82 (q), 155.44, 138.50 (q), 130.96, 127.78, 123.02 (q), 122.27 (q), 118.28, 117.69 and 51.29; m/z 214 (M+, 11%), 212 (M+, 29), 182 (37), 180 (100), 154 (33), 152 (94), 127 (11), 125 (36), 99 (12), 89 (44) and 63 (30). 2-Hydroxy-5-nitrobenzaldehyde gave methyl 3-(2-hydroxy-5-nitrophenyl)propenoate 5 (0.67 g, 75%), mp 198–200 °C (from ethyl acetate); (Found: C, 53.7; H, 4.0; N, 6.0. C10H9NO5 requires C, 53.85; H, 4.1; N, 6.35%); dH 8.48 (1 H, d, 4J 2.8), 8.17 (1 H, dd, 3J 9.1 and 4J 2.8), 7.80 (1 H, d, 3J 16.3), 7.07 (1 H, d, 3J 9.0), 6.80 (1 H, d, 3J 16.3) and 3.70 (3 H, s); dC 166.59 (q), 162.35 (q), 139.78 (q), 137.91, 126.80, 124.94, 121.16 (q), 119.91, 116.49 and 51.45; m/z 223 (M+, 26%), 191 (100), 117 (22), 89 (24) and 63 (13). 2-Hydroxy-1-naphthaldehyde gave methyl 3-(2-hydroxy-1-naphthyl)propenoate 8 (0.77 g, 85%), mp 145–148 °C (from ethyl acetate); (Found: C, 73.3; H, 5.3.C14H12O3 requires C, 73.7; H, 5.35%); dH 8.29 (1 H, d, 3J 16.0), 8.16–7.23 (6 H, m), 6.88 (1 H, d, 3J 16.0) and 3.18 (3 H, s); dC (one quaternary missing), 160.21 (q), 153.47 (q), 140.58, 133.38, 130.04 (q), 128.95, 128.51, 126.26, 122.42, 116.96, 115.49, 113.02 (q) and 48.70; m/z 228 (M+, 50%), 196 (94), 168 (100), 141 (31), 140 (17), 139 (37) and 115 (26).The following compounds were made using ethyl 2-(triphenylphosphoranylidene) propionate (2, R2=Me) in dichloromethane under reflux conditions for 1 h. The same molar amounts of reagents (4 mmol) and similar work-up were used as described in the general method given above.Salicylaldehyde gave ethyl 2-methyl-3-(2-hydroxyphenyl)propenoate 6 (0.67 g, 82%), mp 58–61 °C (from hexane); (Found: C, 69.4; H, 6.8. C12H14O3 requires C, 69.8; H, 6.8%); dH 7.74 (1 H, s), 7.30–6.79 (4 H, m), 4.18 (2 H, q), 1.98 (3 H, s) and 1.26 (3 H, t); dC 167.68 (q), 134.36, 129.87, 129.76, 126.62 (q), 122.15 (q), 118.59, 115.76 (q), 115.32, 60.20, 14.07 and 13.92; m/z 206 (M+, 15%), 160 (100), 132 (40), 131 (31) and 77 (10). 2-Hydroxy-5-chlorobenzaldehyde gave ethyl 2-methyl- 3-(2-hydroxy-5-chlorophenyl)propenoate 7 (0.85 g, 88%), mp 93–95 °C (from n-hexane); (Found: C, 59.8; H, 5.4.C12H13ClO3 requires C, 59.9; H, 5.4%); dH 7.63 (1 H, d, 4J 2.5), 7.26 (1 H, s), 7.21 (1 H, dd, 3J 8.5 and 4J 2.5), 6.90 (1 H, d, 3J 8.5), 4.18 (1 H, q), 1.96 (3 H, s) and 1.25 (3 H, t); dC 167.37 (q), 154.66 (q), 138.18 (q), 132.88, 129.40, 128.87, 128.12 (q), 123.85 (q), 116.94, 60.41, 14.07 and 13.87; m/z 242 (M+, 5%), 240 (M+, 12), 196 (22), 195 (30), 194 (100), 167 (17), 166 (38), 165 (31), 131 (19), 103 (22) and 77 (20).Preparation of Coumarins by Flash Vacuum Pyrolysis.·The appropriate propenoate was distilled at 10µ2–10µ3 Torr into an empty silica pyrolysis tube (35Å2.5 cm) which was maintained at 750 °C by an electrical furnace. The products were collected at the exit point of the furnace in a U-tube cooled with liquid nitrogen, and could be removed by scraping with a spatula or by dissolving them in a solvent.Pyrolysis conditions are given as follows: precursor, quantity of precursor, inlet temperature, furnace temperature, mean pressure, time of the pyrolysis, and product. Methyl 3-(2-hydroxyphenyl)propenoate [(0.063 g, 0.353 mmol), 100 °C, 750 °C, 5Å10µ3 Torr, 5 min] gave coumarin 9 (0.051 g, 87%), mp 68–69 °C (from n-hexane) (lit.,9 68 °C); dH 8.01 (1 H, d, 3J 9.5), 7.60 (2 H, m), 7.34 (2 H, m) and 6.47 (1 H, d, 3J 9.5); dC 159.90 (q), 153.39 (q), 144.16, 131.88, 128.35, 124.42, 118.63 (q), 116.18 and 116.10; m/z 146 (M+, 91%), 118 (100), 90 (29), 89 (17) and 63 (21).Methyl 3-(2-hydroxy-5-chlorophenyl)propenoate [(0.060 g, 0.28 mmol), 100 °C, 750 °C, 5Å10µ3 Torr, 5 min] gave 6-chlorocoumarin 10 (0.048 g, 94%), mp 160–162 °C (from ethanol) (lit.,10 161–162 °C); dH 8.00 (1 H, d, 3J 9.6), 7.84 (1 H, d, 4J 2.5), 7.63 (1 H, dd, 3J 8.9 and 4J 2.5), 7.42 (1 H, d, 3J 8.9) and 6.57 (1 H, d, 3J 9.6); dC 159.39 (q), 152.07 (q), 142.98, 131.42, 128.14 (q), 127.47, 120.03 (q), 118.19 and 117.36; m/z 182 (M+, 34%), 180 (M+, 100), 154 (20), 152 (48), 89 (46) and 63 (35).Methyl 3-(2-hydroxy-5-nitrophenyl) propenoate [(0.065 g, 0.29 mmol), 140 °C, 750 °C, 5Å10µ3 Torr, 5 min] gave 6-nitrocoumarin 11 (0.042 g, 75%), mp 183–184 °C (from toluene) (lit.,11 181–182 °C); dH 8.67 (1 H, d, 4J 2.7), 8.35 (1 H, dd, 3J 9.0 and 4J 2.7), 8.19 (1 H, d, 3J 9.7), 7.56 (1 H, d, 3J 9.0) and 6.65 (1 H, d, 3J 9.7); dC 158.84 (q), 157.14 (q), 143.41 (q), 143.22 (q), 126.44, 124.27, 119.00 (q), 118.00 and 117.75; m/z 191 (M+, 100%), 117 (18), 89 (23) and 63 (20).Ethyl 2-methyl- 3-(2-hydroxyphenyl)propenoate [(0.065 g, 0.31 mmol), 100 °C, 750 °C, 5Å10µ3 Torr, 5 min] gave 3-methylcoumarin 12 (0.041 g, 82%), mp 90–92 °C (from ethanol) (lit.,12 69–70 °C); dH 7.86 (1 H, s), 7.63–7.27 (4 H, m) and 2.09 (3 H, s); dC 159.00 (q), 152.56 (q), 139.47, 130.59, 127.41, 124.82 (q), 124.33, 119.24 (q), 115.82 and 16.60; m/z 160 (M+, 79%), 132 (68), 131 (100), 103 (15) and 77 (29).Ethyl 2-methyl-3-(2-hydroxy-5-chlorophenyl)propenoate [(0.064 g, 0.27 mmol), 100 °C, 750 °C, 5Å10µ3 Torr, 5 min] gave 3-methyl-6-chlorocoumarin 13 (0.049 g, 96%), mp 158–160 °C (from ethanol) (lit.,12 158–159 °C); dH 7.79 (1 H, s), 7.70 (1 H, d, 4J 2.4), 7.54 (1 H, dd, 3J 8.8 and 4J 2.4), 7.38 (1 H, d, 3J 8.8) and 2.08 (3 H, s); dC 160.68 (q), 151.15 (q), 138.17, 130.13, 128.04 (q), 126.46, 126.20 (q), 120.62 (q), 117,79 and 16.70; m/z 196 (M+, 31%), 194 (M+, 100), 168 (21), 167 (25), 166 (41), 165 (77), 131 (20), 103 (20), 77 (17) and 51 (32).Methyl 3-(2-hydroxy-1-naphthyl) propenoate [(0.070 g, 0.30 mmol), 140 °C, 750 °C, 5Å10µ3 Torr, 5 min] gave 5,6-benzocoumarin 14 (0.045 g, 75%), mp 118–120 °C (from ethanol) (lit.,13 117–118 °C); dH 8.26 (1 H, d, 3J 9.8), 8.05 (1 H, d, 3J 8.3), 7.85–7.45 (4 H, m), 7.28 (1 H, d, 3J 8.3) and 6.64 (1 H, d, 3J 9.8); dC (one quaternary missing) 160.76 (q), 153.49 (q), 138.85, 132.86, 129.96 (q), 128.75, 128.47, 125.87, 121.11, 116.66, 115.23 and 112.67 (q); m/z 196 (M+, 100%), 168 (70), 139 (75), 115 (23) and 63 (21).We are grateful to British Petroleum plc for a Research Studentship (to G. A. C.). Received, 8th April 1997; Accepted, 30th April 1997 Paper E/7/02405C References 1 Preliminary Communication, M. Black, J. I. G. Cadogan, G. A. Cartwright, H. McNab and A. D. MacPherson, J. Chem. Soc., Chem. Commun., 1993, 959. 2 R. S. Mali and V. J. Yadav, Synthesis, 1977, 464. 3 For leading references, see D. N. Nicolaides, K. C. Fylaktakidou, C. Bezergiannidou-Balouktsi and K. E. Litinas, J. Heterocycl. Chem., 1994, 31, 173. 4 N. Britto, V. G. Gore, R. S. Mali and A. C. Ranade, Synth. Commun., 1989, 19, 1899. 5 H. Ishii, Y. Kaneko, H. Miyazaki and T. Harayama, Chem. Pharm. Bull., 1991, 39, 3100. 6 R. S. Mali, S. N. Yeola and B. K. Kulkarni, Indian J. Chem., 1983, 22B, 352. 7 R. S. Mali, S. G. Tilve, S. N. Yeola and A. R. Manekar, Heterocycles, 1987, 26, 121. 8 C. L. Hickson and H. McNab, J. Chem. Res. (S), 1989, 176. 9 B. K. Ganguly and P. Bagchi, J. Org. Chem., 1956, 21, 1415. 10 A. Clayton, J. Chem. Soc., 1908, 93, 2016. 11 G. T. Morgan and F. M. G. Micklethwait, J. Chem. Soc., 1904, 85, 1230. 12 K. Sunitha, K. K. Balasubramanian and K. Rajagopalan, J. Org. Chem., 1985, 50, 1530. 143 G. Kauffmann, Ber. Dtsch. Chem. Ges., 1883, 16, 683.
ISSN:0308-2342
DOI:10.1039/a702405c
出版商:RSC
年代:1997
数据来源: RSC
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17. |
Palladium(0)-catalysed Coupling of OrganozincReagents with (E)- or(Z)-2-Halo-1-alkylselanylethenes† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 298-299
De-Yu Yang,
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摘要:
H I RSe H + R1ZnCl H R1 RSe H Pd(PPh3)4(3 mol%) THF addn. at –78 °C, 1 h –30 °C to room temp., 12 h 1 Br H RSe H + R1ZnCl R1 H RSe H Pd(PPh3)4(3 mol%) THF addn. at –78 °C, 1 h –30 °C to room temp., 12 h 2 298 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 298–299† Palladium(0)-catalysed Coupling of Organozinc Reagents with (E)- or (Z)-2-Halo-1-alkylselanylethenes† De-Yu Yang,*a Yi Zhangb and Xian Huanga aDepartment of Chemistry, Hangzhou University, Hangzhou 310028, P.R.China bDepartment of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM88003, USA Stereoselective cross-coupling of organozinc reagents with (E)-2-iodo- or (Z)-2-bromo-1-alkylselanylethenes in the presence of a catalycic amount of Pd(PPh3)4 is accomplished. Palladium-catalysed reactions involving organozinc compounds are of rapidly increasing importance in organic synthesis. 1 Carbon–carbon bond formation via transition metal catalysed cross-coupling reactions is of primary interest in view of the variety of functionalities which can be used.Transition metal catalysed coupling reactions of organozinc reagents with vinyl halides have been previously reported.1b Recently we reported that organozinc reagents stereoselectively coupled with alkenyl diselenides by a Ni-catalysed reaction to afford alkenyl selenides2 which can be stereospecifi- ically converted to the corresponding alkenes by further Ni-catalysed cross-coupling with Grignard reagents.3 However, there are no reported studies to date of the stereoselective cross-coupling of organozinc reagents with haloalkylselanylethenes containing difunctionalized groups. Therefore, we now report a stereoselective coupling reaction of organozinc reagents with (E)-2-iodo- or (Z)-2-bromo- 1-alkylselanylethenes by altering the reaction conditions to provide novel alkenyl selenides.We have recently reported that Pd0-catalysed hydroboration of terminal alkylselanylacetylenes followed by iodination or bromination under basic conditions produced (E)-2-iodoor (Z)-2-bromo-1-alkylselanylethenes,4 respectively.Originally, we attempted to employ the reaction of phenylethynylmagnesium bromide in THF with (E)-2-iodoethylselanylethene in the presence of 3–5 mol% of NiCl2(PPh3)2 to afford the expected product 1a. When the reaction was carried out at room temperature, the yield of the desired product was low because the reaction proceeded with poor stereoselectivity even with low reaction temperatures (Scheme 1).On the other hand, even in the presence of a catalytic amount of NiCl2(PPh3)2 and with phenylethynylzinc chloride instead of the Grignard reagent, the reaction failed to afford a satisfactory yield (23% for 1a). However, after switching the Grignard reagent to phenylethynylzinc chloride, NiCl2(PPh3)2 to Pd(PPh3) (3 mol%) and, when appropriate, altering the reaction temperature, compound 1a was obtained in 81% yield (Scheme 1).The syntheses of compounds 1b–e were also examined by coupling organozinc reagents with (E)-2-iodo-1-alkylselanylethenes in the presence of 3 mol% of Pd(PPh3) (Scheme 1). In a similar reaction, (Z)-2-bromo-1-alkylselanylethenes gave the corresponding products 2 (Scheme 1). The results are listed in Table 1. The stereochemistry of compounds 1 was established using the characteristic coupling constants (J 14.5–16 Hz) of the E-configuration between two olefinic proton signals in the 1H NMR spectrum (3 MHz).Similarly, the Z-configuration of 2 was confirmed by 1H NMR, with a coupling constant of 9.5 Hz between two olefinic proton signals. The results in Table 1 indicate that the Pd0-catalysed coupling reaction proceeded with retention of configuration and occurred at the iodine or bromine position. In conclusion, this synthetic method provides, in high stereoselectivity, novel (Z)- or (E)-alkenyl selenides, especially those containing organoynyl groups (such as 1a, 1c, 1d and 2c) that are difficult to prepare by general methods.7 Experimental The 1H NMR spectra were recorded on an AZ-300 MHz spectrometer with TMS as internal standard.Mass spectra were deter- *To receive any correspondence. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Scheme 1 Table 1 Cross-coupling of organozinc reagents with (E)- or (Z)-haloalkylselanylethenes Organozinc Yieldb reagenta Haloalkylselanylethene Product % aFor the preparation of organozinc reagents, see ref. 5.bIsolated yield after chromatography. cFor compound 1b, see ref. 6J. CHEM. RESEARCH (S), 1997 299 mined by a Finigan 8230 mass spectrometer. IR spectra were obtained in heat capillary cells on a Shimadzu IR-408 spectrometer. Elemental analyses were conducted using a Perkin-Elmer 240B elemental analyser. Silica gel 50 GF254 was used for analytical and preparative TLC.Silica gel columns were prepared using silica gel Q/BKUS 3–91 (100–200 Å mesh). The reactions were carried out under a stream of dry nitrogen. All solvents were dried, deoxygenated and redistilled before use. General Procedure for the Synthesis of (E)- or (Z)-1-Alkylselanyl- 2-alkylethenes 1 or 2.·To a stirred mixture of the haloalkylselanylethene (2 mmol) and Pd(PPh3)4 (0.06 mmol, 3 mol%) at µ78 °C in THF (10 ml), the organozinc reagent (2 mmol) in THF (5 ml) was slowly added and the resulting mixture stirred for 1 h.The reaction temperature was warmed to µ30 °C and then stirred for a further 3 h, followed by stirring for 9 h at room temperature. The reaction was then quenched by pouring the mixture in to saturated aqueous NH4Cl (10 ml) in a separatory funnel. Extraction with pentane (2Å10 ml), washing the combined extracts with saturated aqueous NH4Cl (10 ml), drying with anhydrous MgSO4 followed by filtration, concentration in vacuo and flash chromatography (silica gel, light petroleum (bp 60–90 °C)–EtOAc, 98:2) yielded the pure product 1 or 2 as an oil.(E)-4-Ethylselanyl-1-phenylbut-3-en-1-yne 1a. dH (CDCl3) 7.05–7.56 (5 H, m), 6.97 (1 H, d, J 16 Hz), 6.35 (1 H, d, J 16 Hz), 2.75 (2 H, q, J 7.7 Hz) and 1.74 (3 H, t, J 7.7 Hz). vmax/ cmµ1 2230, 1615, 1594, 1560, 1548 and 955. m/z 236 (M+ +1, 14), 235 (M+, 13), 207 (67) and 127 (100).(Found: M+, 235.1833. C12H12Se requires Mr 235.1868). (E)-1-Pentylselanyloct-1-ene-3-yne 1c. dH (CDCl3) 6.69 (1 H, d, J 15 Hz), 6.07 (1 H, d, J 15 Hz), 2.77 (2 H, t, J 7.5 Hz), 2.44 (2 H, t, J 5.8 Hz), 1.68 (2 H, m), 1.05–1.60 (8 H, m), 0.91 (3 H, t, J 6.5 Hz) and 0.77 (3 H, t, J 6.3 Hz). vmax/cmµ1 2217, 1624 and 945. (Found: M+, 255 and 1149. C13H20Se requires Mr 255.1188). (E)-4-Pentylselanyl-1-trimethylsilylbut-3-en-1-yne 1d. dH (CDCl3) 6.78 (1 H, d, J 15 Hz), 6.14 (1 H, d, J 15 Hz), 2.75 (2 H, t, J 7.5 Hz), 1.65 (2 H, m), 1.10–1.49 (4 H, m), 0.93 (3 H, t, J 6.6 Hz) and 0.31 (9 H, s).vmax/cmµ1 2205, 1613 and 949. (Found: M+, 273.3551. C12H22SiSe requires Mr, 273.3518). (E)-3-Ethoxy-1-ethylselanylbuta- 1,3-diene 1e. dH (CDCl3) 6.37 (1 H, d, J 14.5 Hz), 5.75 (1 H, d, J 14.5 Hz), 4.85 (2 H, s), 3.36 (2 H, q, J 6.7 Hz), 2.21 (3 H, s) and 1.23 (3 H, t, J 6.7 Hz). vmax/cmµ1 1607, 941 and 901. (Found: M+, 191,1282. C7H12OSe requires Mr 191.1312).(Z)-1-Ethylselanyl- 2-phenylethene 2a. dH (CDCl3) 7.0–7.6 (5 H, m), 6.75 (1 H, d, J 10 Hz), 6.24 (1 H, d, J 10 Hz), 2.95 (2 H, q, J 7.9 Hz) and 1.71 (3 H, t, J 7.9 Hz). vmax/cmµ1 1631, 1591, 1552 and 695. m/z 212 (M+ +1, 12), 211 (M+, 10), 183 (55) and 104 (100). (Found: M+, 211.1691, C10H12Se requires Mr, 211.1648). (Z)-1-Methylselanylpenta- 1,4-diene 2b. dH (CDCl3) 6.69 (1 H, d, J 9.7 Hz), 6.18 (1 H, dt, J 9.7, 7.1 Hz), 5.75 (1 H, m), 5.0 (2 H, m), 3.05 (2 H, m), and 2.21 (3 H, s).vmax/cmµ1 1607 and 693. (Found: M+, 161.1017. C6H10Se requires Mr, 161.1050). (Z)-4-Ethylselanyl-1-trimethylsilylbut- 3-en-1-yne 2c. dH (CDCl3) 6.71 (1 H, d, J 9.5 Hz), 6.06 (1 H, d, J 9.5 Hz), 2.78 (2 H, q, J 7.7 Hz), 1.70 (3 H, t, J 7.7 Hz), 0.31 (9 H, s). vmax/ cmµ1 2209, 1618 and 705. (Found: M+, 231.2683. C9H16SiSe requires Mr, 231.2714). (Z)-3-Ethoxy-1-methylselanylbuta-1,3-diene 2d. dH (CDCl3) 6.41 (1 H, d, J 9.5 Hz), 5.81 (1 H, d, J 9.5 Hz), 4.6 (2 H, s), 3.41 (2 H, q, J 6.5 Hz), 2.20 (3 H, s), 1.25 (3 H, t, J 6.5 Hz). vmax/cmµ1 1611, 910 and 707. (Found: M+, 191.1279, C7H12OSe requires Mr 191.1312). We thank the National Natural Science Foundation of China. Received, 22nd April 1997; Accepted, 30th April 1997 Paper E/7/02748F References 1 See reviews: (a) P. Knochel and R. D. Singer, Chem. Rev., 1993, 93, 2117; (b) E. Erdik, Tetrahedron., 1992, 48, 9577. 2 D.-Y. Yang and X. Huang, Tetrahedron Lett., in the press. 3 L. Hercsi, B. Heimaus and C. Allard, Tetrahedron Lett., 1994, 35, 6729. 4 (a) D.-Y. Yang and X. Huang, Synth. Commun., 1996, 26, 4617; (b) D.-Y. Yang and X. Huang, J. Chem. Res. (S), 1997, 62. 5 (a) B. P. Andreini, M. Benetti, A. Carpita and R. Rossi, Gazz. Chim. Ital., 1988, 118, 469; (b) S. Hyuga, N. Yamashina, S. Hara and A. Suzuki, Chem. Lett., 1988, 809; (c) T. Klingstedt and T. Frejd, Organometallics, 1983, 2, 598; (d) E.-i. Negishi and F.-T. Luo, J. Org. Chem., 1983, 48, 1560. 6 D.-Y. Yang and X. Huang, Synth. Commun., 1996, 26, 4369. 7 E. N. Deryagina, M. G. Voronkov and N. A. Korchevin, Russ. Chem. Rev., 1993, 62, 1107.
ISSN:0308-2342
DOI:10.1039/a702748f
出版商:RSC
年代:1997
数据来源: RSC
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18. |
Iron(III)–Ethylenediaminetetraacetic AcidMediated Oxidation of Thiols to Disulfides with MolecularOxygen† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 300-301
Tumula Venkateshwar Rao,
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摘要:
R S H R S S R FeIII–EDTA, O2 pH 7.8–9.6, aq. MeOH 1 2 R = Ph, 4-MeC6H4, 4-MeOC6H4, 2-pyridyl, PhCH2, Bu n, n-C5H11, n-C7H15, n-C8H17 300 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 300–301† Iron(III)–Ethylenediaminetetraacetic Acid Mediated Oxidation of Thiols to Disulfides with Molecular Oxygen† Tumula Venkateshwar Rao,a Bir Sain,a Pappu S. Murthy,a Turaga S. R. Prasada Rao,a Ajay K. Jainb and Girish C. Joshi*a aIndian Institute of Petroleum Dehradun-248 005, India bDepartment of Chemistry, University or Roorkee, Roorkee-247 667, India FeIII–EDTA in aqueous methanol offers a simple environmentally acceptable synthetic tool for oxidizing thiols to the corresponding disulfides by molecular oxygen in excellent yields, under mild conditions and devoid of side reactions.The conversion of thiols into the corresponding disulfides (oxidative S–S coupling) is an important reaction and many stoichiometric reagents have been reported to be effective oxidants for it, such as dichromates,1 chlorochromates,2 manganese dioxide,3 diethyl azodicarboxylate,4 halosilane– chromium trioxide,5 nickel peroxide,6 chromium peoxide,7 diaryl telluroxides,8 tetrabutylammonium cerium(IV) nitrate,9 sodium perborate10 and silver trifluoromethanesulfonate. 11 Owing to the growing environmental concerns surrounding the use of toxic and dangerous oxidants, oxidative catalytic transformations of organic compounds with molecular oxygen have become an area of continued research and development in recent years.12 The catalytic oxidation of thiols present in petroleum fractions to disulfides with molecular oxygen under strongly alkaline conditions using metal phthalocyanines as catalysts has been extensively studied.13 However, there are only a few reports on the synthesis of disulfides by catalytic oxidation of thiols using molecular oxygen as the primary oxidant, with basic alumina,14 cobalt tetrasulfonatophthalocyanine,15 intercalated [MOVIO2(O2CC(S)Ph2)2]2µ in ZnII–AlIII-layered double hydroxide16 and cobalt chlorate17 all having been used as catalysts.The subject has been comprehensively reviewed by Uemura.18 Among the transition metals, iron is singled out as being non-toxic19 and more emphasis is being given on the use of iron-based systems for oxidation.20 Earlier, we reported iron(III)–ethylenediaminetetraacetic acid (FeIII– EDTA) mediated autoxidation of 2,6-di-tert-butylphenol and substituted hydroquinones.21 We now report for the first time FeIII–EDTA22 catalysed oxidation of thiols (1) to disulfides (2) with molecular oxygen (Scheme 1). An FeIII–EDTA (0.1 M) solution was prepared by adding EDTA disodium salt solution to an ammonium iron(III) sulfate solution and raising the pH of the mixture to 8.0 by addition of sodium carbonate solution.The oxidation experiments were carried out by bubbling molecular oxygen into a solution of the thiol in 80% aqueous methanol containing FeIII–EDTA (10 mol% of the thiol) at specified pH under ambient conditions (Table 1).A wide variety of thiols (aromatic, aliphatic and heterocyclic) were selectively oxidized to their corresponding disulfides in near quantitative yields without any evidence for the formation of the corresponding sulfonic acid. Under these reaction conditions aromatic thiols in general were found to be more reactive than aliphatic ones. Among the aliphatic thiols the reactivity was found to decrease with increasing carbon chain length and was strongly dependent upon the pH of the medium.While aromatic thiols could be oxidized at a pH of about 8 in a reasonable reaction time, the aliphatic thiols required a higher pH. To evaluate the catalytic effect of FeIII–EDTA in this reaction, a parallel blank experiment was carried out with benzenethiol. The conversion of benzenethiol into its disulfide was 73% after 4 h without FeIII–EDTA, while conversion was quantitative within 20 min in the presence of FeIII– EDTA.The oxidation of thiols to disulfides by molecular oxygen under alkaline conditions has been reported to proceed through a radical pathway involving one-electron transfer from the thiolate anion to the molecular oxygen. Metal ions are known to catalyse this reaction.23 Accordingly, the mechanistic pathway for the present reaction could be through the formation of a thiyl radical by single-electron transfer from the thiolate anion to the FeIII–EDTA, followed by coupling *To receive any correspondence (e-mail: root%iip@sirnetd. ernet.in).†This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Table 1 FeIII–EDTA catalysed oxidation of thiols (1) to disulfides (2) by molecular oxygena Mp or bp (Torr) (T/°C) Disulfide Reaction Yieldb (2) R pH (t/h) (%) Found Lit.a bc def ghij Ph 4-MeC6H4 4-MeOC6H4 2-Pyridyl PhCH2 PhCH2 Bun n-C5H11 n-C7H15 n-C8H17 7.8 7.9 7.8 8.0 7.8 8.5 9.5 9.5 9.5 9.6 0.33 0.75 1.0 0.50 8389 12 18 96 95 87 84 97 98 93 86 87 88 59–61 47–48 44–45 52–53 70–71 70–71 94(6) 117(6) 152–154(6) 185–187(6) 59–6014 46–4825 43.825 52–5325 69–7014 69–7014 88–91(3)14 90–92(1)26 143–147(5)27 178–83(5)27 aThe reaction was carried out with 40 mmol of alkanethiol or 10 mmol of arenethiol. bYield of pure product isolated by crystallization or distillation.Scheme 1FeIII–EDTA + RS– FeII–EDTA + RS• RS• + RS• R S S R FeII–EDTA + O2 FeIII–EDTA + O2 –• RS– + FeIII(OH–)EDTA FeIII(RS–)EDTA + OH– FeIII(RS–)EDTA FeIIEDTA + RS• J. CHEM. RESEARCH (S), 1997 301 of the radical to yield the disulfide. The FeII–EDTA thus formed is oxidized to FeIII–EDTA by the molecular oxygen (Scheme 2). Wubs and Beenackers24 postulated FeIII(OHµ)EDTA to be the active species in the oxidation of H2S by FeIII–EDTA under alkaline conditions.In accordance with their mechanism, thiols may form complexes with FeIII–EDTA by way of replacement of OHµ and intramolecular electron transfer from FeIII to the thiolate anion generating a thiyl radical (Scheme 3). The wine red colour of FeIII–EDTA is changed to bluish green on addition of a thiol to an alkaline solution of FeIII– EDTA, and again to wine red on complete oxidation of the thiol to the disulfide, suggesting complex formation between the thiolate anion and the FeIII–EDTA.In line with the postulated mechanism, the rate of oxidation would depend on the concentration of thiolate anion. Since aromatic thiols have lower pKa values than aliphatic thiols, sufficient availability of the thiolate anion is expected at lower pH. This is in line with their fast oxidation at pH 18 while aliphatic thiols require higher pH. The simplicity of the system, excellent yields, and the reasonable reaction time thus make FeIII–EDTA an attractive, environmentally acceptable synthetic tool for the oxidation of thiols to disulfide by molecular oxygen.Experimental General Procedure for the Oxidation of Thiols by Molecular Oxygen in the Presence of FeIII–EDTA.·A solution of the thiol (10 mmol) in 80% aqueous methanol (50 ml) containing FeIII–EDTA (0.1 mmol; 10 ml of 0.1 M solution) was taken in a two-necked roundbottomed flask fitted with gas delivery tube and a condenser. The pH of the solution was adjusted by adding a few drops of an alkali solution and oxygen gas was passed into the solution at 30 °C for a specified period (Table 1).The completion of the reaction was indicated by the colour change of the reaction mixture from bluish green to wine red. The major portion of the methanol was then removed by distillation under reduced pressure, followed by dilution of the reaction mixture with water (40 ml) and extraction with dichloromethane (3Å30 ml). The combined dichloromethane extract was washed with water and dried (Na2SO4).Removal of the solvent under reduced pressure yielded the desired disulfide. The disulfides were purified either by recrystallization or by vacuum distillation. The identity of the products was established by comparison of their mps (wherever possible), IR and NMR spectra and GC retention times. Received, 25th March 1997; Accepted, 6th May 1997 Paper E/7/02061I References 1 C. Lopez, A. Gonzalez, F. P. Cossio and C. Palomo, Synth. Commun., 1985, 15, 1197. 2 E. Santaniello, F. Milani and R. Casati, Synthesis, 1983, 749. 3 E. P. Papadopoulos, A. Jarrar and C. H. Issidorides, J. Org. Chem., 1966, 31, 615. 4 F. Yoneda, K. Suzuki and Y. Nitta, J. Org. Chem., 1967, 32, 727. 5 J. M. Aizpurua, M. Juaristi, B. Lecea and C. Palomo, Tetrahedron, 1985, 41, 2903. 6 K. Nakagawa, S. Shiba, M. Horikawa, K. Sato, H. Nakamura, N. Harada and F. Harada, Synth. Commun., 1980, 10, 305. 7 H. Firouzabadi, N. Iranpoor, F.Kiaeezadeh and J. Toofan, Tetrahedron, 1986, 42, 719. 8 S. V. Ley, C. A. Meerholz and D. H. R. Barton, Tetrahedron, Suppl., 1981, 213. 9 H. A. Muathen, Indian J. Chem., 1991, 30B, 522. 10 A. McKillop, D. Koyuncu, A. Krief, W. Dumont, P. Renier and M. Trabelsi, Tetrahedron Lett., 1990, 31, 5007. 11 H. Tamamura, A. Otaka, J. Nakamura, K. Okubo, T. Koide, K. Ikeda and N. Fujii, Tetrahedron Lett., 1993, 34, 4931. 12 L. I. Simandi, Catalytic Activation of Dioxygen by Metal Complexes, Kluwer, Boston, 1992; The Activation of Dioxygen and Homogeneous Catalytic Oxidation, ed.D. H. R. Barton, A. E. Martel and D. T. Sawyer, Plenum Press, New York, 1993. 13 S. Basu, S. Satapathy and A. K. Bhatnagar, Catal. Rev.-Sci. Eng., 1993, 35, 571. 14 K.-T. Liu and Y.-C. Tong, Synthesis, 1978, 669. 15 A. K. Yatsimirskii, E. I. Kozlyak and A. S. Erokhin, Kinet. Catal., 1988, 29, 305. 16 A. Cervilla, A. Corma, V. Fornes, E. Lopis, P. Palanca, F. Rey and A. Ribera, J. Am. Chem. Soc., 1994, 116, 1595. 17 L. I. Simandi, S. Nemeth and N. Rumelis, J. Mol. Catal., 1987, 42, 357. 18 S. Uemura, in Comprehensive Organic Synthesis, ed. B. M. Trost and I. Fleming, Pergamon Press, New York, 1991, vol. 7, pp. 757–787. 19 W. A. Knepper, in Kirk-Othmer Encyclopedia of Chemical Technology, Wiley, New York, 3rd edn., 1981, vol. 13, pp. 735–753. 20 D. Lionel and P. Laszlo, J. Org. Chem., 1996, 61, 6360. 21 B. Sain, P. S. Murthy, T. Venkateshwar Rao, T. S. R. Prasada Rao and G. C. Joshi, Tetrahedron Lett., 1994, 35, 5083. 22 J. R. Hart, Chemtech., 1987, 17, 313. 23 C. F. Cullis, J. D. Hopton, C. J. Swan and D. L. Trimm, J. Appl. Chem., 1968, 18, 335. 24 H. J. Wubs and A. A. C. M. Beenackers, AIChE J., 1994, 40, 433. 25 G. A. Olah, M. Arvanaghi and Y. D. Vankar, Synthesis, 1979, 721. 26 E. Miller, F. S. Crossley and M. L. Moore, J. Am. Chem. Soc., 1942, 64, 2322. 27 H. E. Westlake Jr and G. Dougherty, J. Am. Chem. Soc., 1942, 64, 149. Scheme 2 Scheme 3
ISSN:0308-2342
DOI:10.1039/a702061i
出版商:RSC
年代:1997
数据来源: RSC
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19. |
Synthesis of 2,3-Di-(2-adamantylidene)succinic Anhydride:a Highly Non-photochromic Overcrowded Fulgide† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 302-303
Abdullah M. Asiri,
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摘要:
OR OMe O O a R = H b R = Me 2 OMe OH O O 5 OH OH O O 3 OH OH O O 6 4 7 O O O O O O O O O O Me Me Me 1 302 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 302–303† Synthesis of 2,3-Di-(2-adamantylidene)succinic Anhydride: a Highly Non-photochromic Overcrowded Fulgide† Abdullah M. Asiri Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, P.O. Box 9027, Saudi Arabia A two-step Stobb�e condensation of adamantan-2-one with dimethyl succinate and then dimethyl (2-adamantylidene) succinate affords a half-ester 5, which on hydrolysis and dehydration gives the title fulgide 7.Stobb�e1 first introduced the term ‘fulgide’ to describe derivatives of 2,3-di(methylidene)succinic anhydride. Since the beginning of this century many fulgides have been prepared and their photochromic properties investigated.2–4 Heller and co-workers5 synthesised (E)-2-(2-adamantylidene)- 3-[1-(2,5-dimethyl-3-furyl)ethylidene]succinic anhydride 1 as the first example of a photochromic fulgide containing the rigid and bulky adamantylidene group.In view of our long standing interest in the development of novel fulgides for application in the field of optical data storage, the synthesis of non-photochromic highly overcrowded 2,3-di(2-adamantylidene) succinic anhydride and its mono derivative were undertaken. Stobb�e condensation of adamantan-2-one and dimethyl succinate in toluene using potassium tert-butoxide as a base afforded 1-methyl hydrogen 2-(2-adamantylidene)succinate 2a (Scheme 1).The composition of the acid ester 2a was confirmed by hydrolysis to the diacid 3, which was converted into (2-adamantylidene)succinic anhydride 4 by boiling with acetyl chloride. The mass spectrum of the cyclic anhydride 4 showed a molecular ion at m/z 232 and a base peak at m/z 160, which corresponds to the loss of one molecule of both carbon monoxide and carbon dioxide. The acid ester 2a was re-esterified to give dimethyl (2-adamantylidene)succinate 2b using acetyl chloride and methanol.A second Stobb�e condensation of the diester 2b and adamantan- 2-one afforded methyl hydrogen 2,3-di(2-adamantylidene) succinate 5. The latter was hydrolysed by boiling in 10% alcoholic KOH to give the diacid 6 as a colourless powder, which was cyclised to the title fulgide 7 in boiling acetyl chloride. The mass spectrum of 7 showed the base peak at m/z 364, in agreement with its chemical composition C24H28O3. To the best of our knowledge, 7 is believed to be the most overcrowded fulgide prepared so far.Experimental Melting points were determined on a Reichardt hot-stage microscope and were uncorrected. 1H NMR spectra were obtained for solutions in CDCl3 with Me4Si as internal standard using a Bruker WM360 spectrometer. Mass spectra were recorded on a Varian MAT CH5 spectrometer. Microanalyses were carried out using a Perkin Elmer 240B analyser. IR spectra were recorded for solutions on a Perkin Elmer 1600 FTIR spectrometer. 1-Methyl Hydrogen 2-(2-Adamantylidene)succinate 2a.·A mixture of dimethyl succinate (75 g, 0.51 mol) and adamantan-2-one (75 g, 0.50 mol) in warm dry toluene (250 ml) was added dropwise to a suspension of potassium tert-butoxide (56 g, 0.50 mol) in dry toluene (150 ml) with stirring at room temperature. When the addition was complete, the reaction mixture was stirred for a further 12 h and then poured onto crushed ice (250 g) and stirred for 10 min.The toluene layer was separated and washed with water (2Å50 ml). The combined aqueous solutions were acidified with concentrated hydrochloric acid to liberate the acid ester 2a as a colourless powder which was recrystallised from acetone as colourless cubes (62 g, 64%), mp 136–139 °C (lit.,5 138–139 °C). Dimethyl (2-Adamantylidene)succinate 2b.·Methyl hydrogen (2-adamantylidene)succinate (60 g, 0.23 mol) was dissolved in absolute methanol (250 ml). Acetyl chloride (25 ml) was added dropwise with stirring at room temperature over a period of 30 min.When the addition was complete the mixture was refluxed for 6 h. The solvent was removed under reduced pressure and the residue was distilled under vacuum to afford the diester 2b as pale yellow oil (56 g, 89%), bp 145–160 °C at 1 mmHg; dH 1.78–2.0, 2.88 (14 H, m, adamantylidene), 3.38 (2 H, s, CH2), 3.66 (3 H, s, CH3O), 3.70 (3 H, s, CH3O). 2-Adamantylidenesuccinic Anhydride 4.·A warm solution of 10% ethanolic potassium hydroxide (100 ml) was added to the acid ester 2a (2 g, 7.57 mmol) and then the solution was boiled for 6 h.The solvent was removed and the residual dipotassium salt was dissolved in water (100 ml) and acidified with concentrated hydrochloric acid. The liberated diacid 3 was extracted with diethyl ether (2Å50 ml), dried (MgSO4) and filtered and the diethyl ether was removed from the filtrate under reduced pressure to give the diacid 3.The latter was dehydrated by boiling with acetyl chloride (50 ml) †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J. Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Scheme 1J. CHEM. RESEARCH (S), 1997 303 for 3 h. The excess of acetyl chloride was removed under reduced pressure and the residue crystallised from ethanol to give the anhydride 4 as pale yellow cubes (0.9 g, 51%), mp 174–175 °C; dH 1.50–2.20, 3.43 (14 H, m, adamantylidene), 3.30 (2 H, s, CH2); vmax/ cmµ1 1806 (C�O), 1753 (C�O); m/z 258 (14%, M+), 232 (73), 188 (68), 160 (100), 117 (48) (Found: C, 72.65; H, 6.97.C14H16O3 requires C, 72.41; H, 6.90%). 2,3-Di(2-adamantylidene)succinic Acid 6.·A mixture of adamantan- 2-one (15 g, 0.1 mol) and dimethyl (2-adamantylidene) succinate (28 g, 0.1 mol) in toluene (100 ml) was added dropwise with stirring to a suspension of potassium tert-butoxide (100 ml) in toluene (50 ml) at room temperature.Stirring was continued for 12 h. Work-up as described for compound 1a gave the acid ester 5 as a brown gum, which was hydrolysed as described for compound 3 to afford the diacid 6 which was recrystallised from ethanol– chloroform (1:1 v/v) as a colourless powder (7.5 g, 49%), mp 288 °C (Found: C, 75.26; H, 7.93. C24H30H4 requires C, 75.39; H, 7.85%). 2,3-Di(2-adamantylidene)succinate Anhydride 7.·A mixture of the diacid 6 (5 g, 13.1 mol) was boiled with acetyl chloride (20 ml) for 10 h. Work-up as described for compound 4 gave the crude fulgide as white powder (3.8 g, 80%). Recrystallisation from toluene gave the fulgide 4 as white needles, mp 258–260 °C; dH 1.1–2.50, 4.20 (14 H, m, adamantylidene); vmax/cmµ1 1809 (C�O), 1756 (C�O); m/z 364 (100%, M+), 366 (14), 292 (21) (Found: C, 79.26; H, 7.83%. C24H28O3 requires C, 79.12; H, 7.69%). Received, 14th April 1997; Accepted, 6th May 1997 Paper E/7/02515G References 1 H. Stobb�e, Ber. Dtsch. Chem. Ges., 1904, 37, 2236. 2 L. Chalkley, Chem. Rev., 1929, 6, 217. 3 R. Exelby and R. Grinter, Chem. Rev., 1965, 65, 247. 4 J. Whittal, in Photochromism Molecules and Systems, ed. H. Durr and H. Bouas-Laurent, Elsevier, Amsterdam, 1990, pp. 467–492. 5 A. Glaze, H. G. Hiller and J. Whittal, J. Chem. Soc., Perkin Tr
ISSN:0308-2342
DOI:10.1039/a702515g
出版商:RSC
年代:1997
数据来源: RSC
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20. |
Cadmium(II) Complex withL-Carnosineas a Ligand and the Tautomeric Change of the Imidazole Moietyupon Complexation† |
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Journal of Chemical Research, Synopses,
Volume 0,
Issue 8,
1997,
Page 304-305
Asit R. Sarkar,
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摘要:
304 J. CHEM. RESEARCH (S), 1997 J. Chem. Research (S), 1997, 304–305† Cadmium(II) Complex with L-Carnosine as a Ligand and the Tautomeric Change of the Imidazole Moiety upon Complexation† Asit R. Sarkar* and Mitali Sarkar Department of Chemistry, University of Kalyani, Kalyani-741235, W.B., India L-Carnosine functions as a quadridentate ligand in a novel cadmium(II) complex in which the imidazole moiety of the ligand undergoes tautomeric change during complex formation; the process has been characterised by infrared and 13C NMR spectroscopy. L-Carnosine (b-alanyl-L-histidine) (1) is used in the treatment of surgical wounds, gastric ulcers, arthritis, inflammations and diseases caused by active oxygen.1 The interactions of this ligand with bivalent zinc, both in solution2 and in the solid state,3 have been reported.L-Carnosine acts as a bridging dianionic ligand following removal of the amide and carbonyl protons in its copper(II) complex.4 The ligand coordinates to one copper centre through its three donor atoms, namely the oxygen of the carboxylate group, the nitrogen of the NH2 group and another nitrogen of the deprotonated amide group.The same ligand binds the other copper centre through N(1) of the imidazole moiety. Cadmium occupies an interesting position in the periodic table, being placed in group 12 between zinc and mercury, both of which play essential roles in several biological processes.5,6 It is thus interesting to study the interaction of cadmium(II) ion with L-carnosine.In this paper we report our preliminary findings on the isolation and characterisation of a novel complex of cadmium(II) with L-carnosine. We propose the formulation for the isolated complex as CdL.H2O, where H2L=L-carnosine. The TGA curve of the complex shows a loss of weight at around 130 °C and the gradual decomposition continues up to 350 °C without the formation of any stable intermediate. The decrease in the IR absorption frequency of the amide carbonyl band in the complex (1620 cmµ1) by 36 cmµ1 compared with the free ligand value (1656 cmµ1) indicates the loss of hydrogen from the amide nitrogen7 followed by the coordination to cadmium(II).Similar behaviour of the amide carbonyl frequency is also reported8 in zinc(II) complexes with glycil-L-histidine and L-alanyl-L-histidine. Both symmetric and asymmetric stretching vibrations of the carboxyl group (1408 and 1582 cmµ1, respectively) also shift to lower frequencies in the complex indicating coordination through the carboxylate oxygen of the ligand.The strong band (3250 cmµ1) in the complex suggests coordination through the nitrogen of the primary amine group of the ligand. This band disappears in the deuterated complex. Thus the qualitative interpretation of the IR spectral data suggests that L-carnosine is coordinated to cadmium(II) through its three donor atoms, namely, the oxygen of the carboxylate group and two nitrogen atoms, one from the primary amine and the other from the deprotonated amide group.We could not get any information from the IR spectrum regarding the coordination through the ring nitrogen of the imidazole moiety which is also a potential donor atom. Table 1 shows the 13C NMR spectra of L-carnosine (1) and the prepared cadmium(II) complex. The signals of L-carnosine are assigned as reported in the literature.9 The imidazole moiety of L-carnosine exists in the N(3)·H tautomeric form in the solid state.10 The C(2) and C(5) chemical shifts for L-carnosine overlap at 135.7 ppm but split into 148.9 and 135.3 ppm respectively for its cadmium(II) complex 2.The C(2) and C(5) signals in the complex show downfield shifts of 13.2 and 12.5 ppm respectively to that of the free ligand L-carnosine suggesting a drastic ligand change upon complexation. The 13C NMR spectra of imidazole 3 L-histidine 4, cyclo-L-methionine-L-histidine 5 and their respective zinc(II) complexes [6–8, respectively] are also recorded and presented in Table 1.The imidazole moiety exists in the N(3)·H form11 in the free ligand. The chemical shifts for imidazole and its zinc(II) complex 6 remain almost unaffected for the C(2) and C(5) atoms (0.9 ppm downfield and 1.2 ppm upfield respectively). The resonance signal of the complex 6 shifts downfield by 4.1 ppm compared to free imidazole for the C(4) atom. Again the C(2) and C(5) signals for the zinc(II) complex of L-histidine 7 also do not change appreciably (0.6 upfield and 1.0 ppm downfield) as compared with L-histidine.The C(4) signal in the complex 7 shows a downfield shift (1.5 ppm) compared with L-histidine. The imidazole moiety exists in its N(3)·H tautomeric form12 in both the complexes of zinc(II) with imidazole and L-histidine and N(1) coordinates to zinc(II).13 The C(2) and C(5) signals in the zinc(II) complex of cyclo-L-methionine-L-histidine 8 shift to 4.2 ppm downfield and 6.8 ppm upfield with respect to the free ligand 5.Also the C(4) signal shifts downfield by 4.8 ppm. These changes for the above complex 8 with respect to the free ligand 5 are in the same direction as in the case of the prepared cadmium(II) complex of L-carnosine, in comparison with the free ligand. The imidazole moiety exists in the *To receive any correspondence. †This is a Short Paper as defined in the Instructions for Authors, Section 5.0 [see J.Chem. Research (S), 1997, Issue 1]; there is therefore no corresponding material in J. Chem. Research (M). Table 1 13C NMR data for 1–8 dC Compound CO2 N(H)CO C(2) C(5) C(4) C(ap) 12364758 177.9 176.9 175.7 178.0 169.1 172.0 170.0 167.9 135.7 148.9 136.3 137.2 137.4 136.8 134.9 139.1 135.7 135.3 126.8 125.6 135.8 136.8 134.9 128.1 115.1 127.6 115.3 119.4 113.8 115.3 119.1 123.9 33.8 38.3 52.9 54.8HN N NHC CO2H NH2 a b¢ a¢ b 1 HN N 3 1 2 3 4 5 HN N Cd N C O O C H2N O N Cd N C O O C NH2 O 1 2 34 5 HN 1 2 3 4 5 2 HN N 4 NH2 CO2H HN N 5 NH C C HN SMe HN N 6 ZnCl2 N NH 8 NH C C HN SMe HN N HN CO2 2 Zn 2 Zn 4 Cl2 7 1 2 3 4 5 1 2 3 4 5 O O O O O J.CHEM. RESEARCH (S), 1997 305 N(3)·H form in cyclo-L-methionine-L-histidine11 but, in its complex with zinc(II), the imidazole moiety exists in the N(1)·H form in the solid state.14 Hence on the basis of the above discussions we can conclude that in the prepared cadmium( II) complex of L-carnosine, the imidazole moiety is present in its N(1)·H form showing the change of the tautomeric form on complexation.Our conclusion is also consistent with the observations of Friedlich and Wasylishen9 who recorded the 13C NMR spectra of various histidine derivatives. The ring nitrogen at N(3) will coordinate to cadmium( II). Simultaneous binding of all the four donor atoms of the ligand to the same CdII centre will not be feasible due to severe ring strain by the coordination of the ring nitrogen at N(3).Hence we propose that the ligand acts as a bridge between two CdII centres as shown in compound 2. The signals for the amide carbonyl and the ap-carbon in the cadmium( II) complex (Table 1) shift downfield by 2.9 and 4.5 ppm respectively with respect to L-carnosine indicating the participation of the amide group in the coordination. Experimental 13C-CP/MAS NMR spectra were recorded in the solid state on JEOL GSX 400NB spectrometer with Me4Si as internal standard.IR spectra were recorded on a PE983 spectrophotometer. Thermogravimetric analysis was carried out with a Derivatograph (System: F. Paulik, J. Paulik and L. Erdey, MOM, Budapest). The finely powdered substances were heated at the rate of 2 °C per minute. L-Carnosine and other histidine derivatives were from Sigma, USA. Other chemicals used were of analytical grade. The cadmium complex of L-carnosine was prepared by adding a saturated aqueous solution of CdCl2.2.5H2O (2.28 g, 10 mmol) to a solution of L-carnosine (2.26 g, 10 mmol).The pH of the L-carnosine solution was maintained at ca. pH 7.5 by adding dilute NaOH. The resultant clear solution was stirred and the pH fell below 7.0. The volume of the solution was reduced to one third by heating over a water bath. On cooling white crystals gradually appeared. The yield was 38%. The zinc(II) complexes of imidazole,15 L-histidine13 and cyclo-L-methionine-L-histidine14 were prepared by earlier methods as reported in the literature.The cadmium content was estimated gravimetrically as molybdate after decomposing the complex in a platinum crucible at 800 °C with HNO3 and finally with H2SO4. (Found: Cd, 32.35; C, 31.02; H, 3.67; N, 16.28. Cd (C9H12N4O3).H2O requires Cd 31.71; C, 30.47; H, 3.95; N, 15.80%). The analytical data of the zinc(II) complexes are within 1% of reported data.13–15 Received, 7th August 1996; Accepted, 6th May 1997 Paper E/6/05510I References 1 D.W. Fitzpatrick and H. Fisher, Surgery, 1982, 91, 56; R. Kochen, Y. Yamamoto, K. C. Cundy and B. N. Ames, Proc. Natl. Acad. Sci. USA, 1988, 85, 3175. 2 B. Martin and J. T. Edsal, J. Am. Chem. Soc., 1960, 82, 1107; G. R. Lenz and A. E. Martell, Biochemistry, 1964, 3, 750. 3 T. Matsukura, T. Tokahasi, Y. Nishimura, T. Ohtani, M. Sawada and K. Shibat, Chem. Pharm. Bull., 1990, 38, 3140. 4 H. C. Freeman and J. T. Szymanski, Acta Crystallogr., 1967, 22, 406. 5 G. J. Brewer, Metal Ions in Biological Systems, ed. H. Sigel, Marcel Dekker, New York, 1982, vol. 14, p. 57. 6 A. J. Carty and N. J. Taylor, Inorg. Chem., 1977, 16, 177. 7 A. Lukton and A. Sisti, J. Org. Chem., 1961, 26, 617. 8 D. L. Rabenstein, S. A. Diagnault, A. A. Isab, A. P. Arnold and M. M. Shoukry, J. Am. Chem. Soc., 1985, 107, 6435. 9 J. O. Friedlach and R. E. Wasylishen, Can. J. Chem., 1986, 64, 2132. 10 H. Itoh, T. Yamane, T. Ashida and M. Kakudo, Acta Crystallogr., Sect. B, 1977, 33, 2959. 11 M. Bressman, F. Marchiori and G. Valle, Int. J. Peptide Protein Res., 1984, 23, 104. 12 J. J. Madden, E. L. McGundy and N. C. Seeman, Acta Crystallogr., Sect. B, 1972, 38, 2377. 13 R. H. Krestinger, F. A. Cotton and R. F. Bryan, Acta Crystallogr., 1963, 16, 651. 14 Y. Kojima, K. Hirotsu, T. Yamashita and T. Miwa, Bull. Chem. Soc. Jpn., 1985, 58, 1894. 15 C. Sandmark and C. I. Branden, Acta Chem. Scand., 1967, 21, 993. Fig. 1 L-Carnosine 1, other histidine derivatives and their complexes
ISSN:0308-2342
DOI:10.1039/a605510i
出版商:RSC
年代:1997
数据来源: RSC
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