摘要:

J. CHEM. SOC. PERKIN TRANS. I 1987 Regiospecif ic Arylation of 1,4-Benzoquinone Cyanohydrin Phosphate: Synthesis of 3-Aryl -4- hyd roxybenzon itriles Takushi Kurihara," Shinya Harusawa, Jun-ichi Hirai, and Ryuji Yoneda Osaka University of Pharmaceutical Sciences, 2-10-65,Kawai, Matsubara, Osaka 580,Japan Reaction of 1,4-benzoquinones (1a,b) with diethyl phosphorocyanidate and lithium cyanide was found to give the monocyanophosphates (2a,b). When catalysed by BF,-OEt,, the cyanophosphates (2a,b) reacted with aromatic and heteroaromatic compounds (indole, thiophene, and furan derivatives) to give 3-aryl-4- hydroxybenzonitriles. Under the same conditions ethyl 1-methylindole-2-carboxy late and 2,5-d imet hylf u ran were converted into 6-0x0 benzopyra no [3,441indole-2-carbonitriles (15a,b) and benzofuran-5-carbonitriles (22a,b) by reaction with the cyanophosphates (2a, b), respectively.In a previous paper,' we reported the development of a new and high yield synthesis of +unsaturated nitriles from aromatic ketones via a reaction sequence involving cyano- phosphorylation using diethyl phosphorocyanidate [DEPC, (EtO),P(O)CN] in the presence of lithium cyanide (LiCN) followed by dephosphorylation with BF,*OEt,. Previously Evans and his co-workers reported a general method for the reverse protection of a 1,4-benzoquinone carbonyl group using trimethylsilylcyanide (TMSCN).' With this in mind we have examined the reaction of 1,4-benzoquinones (la) and (Ib) with DEPC and LiCN, since the 1,4-benzoquinone-TMSCN adduct is closely related to 1,4-benzoquinone cyanohydrin pho~phate.~ We now report the cyanophosphorylation of (la,b), and use of the products (2a,b) in the synthesis of biaryls (3-aryl-4- hydroxybenzonitriles), a process related to the Meerwein aryl- ation of quinone~.~ -(1a.b) 6.' OH (3a.b) a: RLH b : R2=OMe I 0 (2a.b) a : RLH 1b : RZ=OMe ii CN (4a.b) RZ=H (5a.b) R2= 2'-Me (5n',b') R2=4' -Me (6a.b) R2=2'-Me85'-Me (7a,b) R = 2 -Me, 4' -Me (8a.b) R2=5',6'-CLHL (gal R2=2'-OMe (9a') R2 = 4' -0Me Scheme 1. Reagetrts: i DEPCILiCN;ii ArRZ/BF,.OEt, t The mechanism for the formation of (3a) is not yet clear. Treatment of compound (la) with DEPC (1.2 equiv.) and LiCN (0.3 equiv.) in THF at room temperature gave the mono- cyanophosphate (2a) (56%), accompanied by 4-hydroxybenzo- nitrile (3a)t (5%).The structure of (2a) was confirmed by ix., H n.m.r. and mass spectroscopic evidence (see Experimental section). When the cyanophosphate (2a)was boiled under reflux in dry benzene in the presence of BF,-OEt, (3 equiv.) for 1 h, 4-hydroxy-3-phenylbenzonilrile(4a) (78%) was obtained as a sole product (Scheme 1). The reaction did not proceed without a catalyst even with a longer reaction time. The structure of (4a) was confirmed on the basis of the spectral evidence and by comparison of its melting point with that of an authentic material.5 The noteworthy regioselective introduction of the benzene ring may be explained by an SN2' process whereby BF, co-ordinates with the phosphate oxygen,6 and thus precedes nucleophilic attack of the benzene on the allylic position; this is followed by aromatisation. Table 1 summarises the results with other aromatic compounds as well as the results of the reaction of the 2-methoxy analogue (2b) with aromatic compounds. Heteroaromatic compounds can also function as the nucleo- philic species, 1-substituted and 1,2-disubstituted indoles reacting with compounds (2a) and (2b) in the presence of BF,*OEt, in acetonitrile to give 3-phenylindoles (10a,b), (1la), (12a), and (13a); 1,3-dimethyIindole afforded the 2-phenylindole derivative (14) on reaction with (2a,b) (see Table 2).Ethyl 1-methylindole-2-carboxylate was found to react with (2a,b) in the presence of BF,-OEt, in acetonitrile to give 6-oxobenzo- pyrano[3,4-b]indole-2-carbonitrile (15a,b) in 30% and 15% yields, respectively, via an intermediate (16a,b) (Scheme 2).Thio- phenes and furans similarly treated with (2a,b) gave the 2-fury1 and 2-thienyl substituted derivatives of benzonitrile (17a), (18a), (19a,b) and (20a,b) (see Table 2) while 2,5-dimethylthiophene afforded 3-(2,5-dimethyl-3-thienyl)-4-hydroxybenzonitrile (21) in low yield. In contrast to the reaction of 2,5-dimethylthiophene, treatment of 2,5-dimethylfuran with (2a) provided the unexpected product of 2-methyl-3-(2-oxopropyl)benzofuran-5-carbonitrile (22a) (34%). The structure of (22a) was supported by its analytical and spectral data (see Experimental section).Similarly, 6-methoxybenzofuran-Scarbonitrile (22b) was obtained from (2b) in 49% yield (Scheme 3). The conversion of 2,s-dimethylfuran into the benzofuran-5-carbonitriles (22a,b) can be explained by the following reaction mechanism: initial arylation of 2,s-dimethylfuran gave the intermediate species 3-arylfurans (23a,b), which upon a subsequent ring-cyclisation ring-opening sequence gave the benzofurans (22a,b), as depicted in Scheme 4. The unsymmetrical 25 1772 J. CHEM. SOC. PERKIN TRANS. I 1987 Table 1. Physical properties and analytical data for the 3-aryl4hydroxybenmnitriles Found (%) Yield (%) Solvent M.p. ("C) C (Required) H 7 N 78 Benzene-Hexane 125-127 79.9 4.6 7.15 83' Benzene-Hexane 146-148 (79.98) 80.35 (4.65) 5.0 (7.17) 6.4 82 Benzene 150-152 (80.36) 80.75 (5.30) 5.9 (6.69) 6.35 96 Benzene 124-126 (80.69) 80.9 (5.87) 6.1 (6.27) 6.35 75 Benzene-Hexane 172-1 74 (80.69) 83.5 (5.87) 4.3 (6.27) 5.95 72' Benzene-Hexane 170-172 (83.24) 76.3 (4.52) 5.25 (5.71) 5.65 18 Benzene 214-215 (76.47) 74.95 (5.22) 4.85 (5.57) 6.25 28' Benzene (74.65) 75.1 (4.92) 5.6 (6.22) 5.65 52 Benzene 158-160 (75.30) 76.15 (5.48) 6.0 (5.85) 5.40 46 Benzene 124-126 (75.87) 76.0 (5.97) 5.8 (5.53) 5.50 39 Benzene 192- 193 (75.87) 78.8 (5.97) 4.7 (5.53) 5.O (78.53) (4.76) (5.09) a This reaction was carried out in a substrate as solvent.This reaction was carried out in refluxing acetonitrile. 'This represents a combined yield of 2'-and 4'abstituted derivatives [(5%)/(5a')= 3:7 and (%)/(%') = 2:8, analysed by 'Hn.m.r.1, but only (5')and (9a') were isolated in a pure form.'This represents a combined yield of (5b)and (Sb') (cu. 6:4, analysed by 'H n.m.r.), but these were not separated in a pure form. Table 2. Physical properties and analytical data for the 3-indolyl-, 3-thienyl-, and 3-furyl-4-hydroxybenonitriles Found (%) (Required) Yield M.p. 7 \ (7% Solvent ("C) C H N 41 MeOH-Hexane 229-23 1 77.25 4.85 11.05 (77.49) (4.87) (1 1.28) 41 Benzene 170-172 77.75 5.35 10.8 (77.84) (5.38) (10.68) 60 Pr'OH 227-229 78.0 5.65 10.7 (77.84) (5.38) (10.68)36 EtOH 265-266 81.6 5.2 8.4 (81.46) (4.97) (8.64)51 AcOEt-Benzene 240-242 73.3 5.03 10.05 (73.36) (5.07) (10.07) 38 Benzene 192-1 94 77.9 5.4 10.45 (77.84) (5.38) (10.68)20 Benzene-Ligroin 110-1 12 65.85 3.5 7.0 (65.65) (3.51) (6.96)49 Benzene-Hexane 108-109 67.0 4.2 6.55 (66.95) (4.21) (6.51) 41 Benzene 158-160 70.85 4.05 7.5 (70.96) (4.33) (7.52) 55 Benzene-Hexane 156-1 58 72.4 4.55 7.05 (72.35) (4.55) (7.03)31 AcEOt 234-235 66.85 4.2 6.4 (66.97) (4.22) (6.5 1)44 Benzene 180-183 68.1 4.8 6.15 (68.1 1) (4.84) (6.1 1)8 Benzene-Ligroin 142-144 68.35 4.9 6.05 (68.09) (4.84) (6.11) J.CHEM.SOC. PERKIN TRANS. I 1987 (15a.b) (1Oa.b) R2= Me,R3=H (lla) R2= Et ,R3=H (12a) R2=Me,R3=Me (130) R2=Me, R3=Ph CN a :RLH b :R1=OMe Scheme 2. (22 a.b) (lea) X =S,R2=MeI MevMe (19a.b) X = 0.R2 =H (2Oa.b)X = 0.R2=Me CN a:R'=H b : R1 =OMe Scheme 3.CN H+ -Me LOH H (23a.b) 1 (22 a. b) f--Me Scheme 4. disubstituted furan 2-methyl-5-propylfuran gave a ca. 1:1 (by 'H n.m.r. analysis) mixture of the benzofurans (24) and (25) in 42% combined yield. The structures of (24) and (25), partially separated by chromatography on SO,, were established from their spectral data, especially from mass spectroscopy (see Experimental section). Experimental 'H N.m.r. spectra were determined with a Varian XL-300 spectrometer (tetramethylsilane as an internal standard), mass spectra with a Hitachi M-80 instrument, and i.r. spectra with a Shimadzu IR-435 spectrometer. Extracts from the reaction mixture were dried over anhydrous sodium sulphate.Diethjd 1-Cyano-4-oxocyclohexa-2,5-dienylPhosphate (2a).-A mixture of 1,4-benzoquinone (la) (1.08 g, 10 mmol), DEPC (1.95 g, 12 mmol), and LiCN (0.1 g, 3 mmol) in THF (50 ml) was stirred at room temperature for 2 h. The solvent was removed under reduced pressure and the residue was dissolved in water (10 ml) and EtOAc (30 ml). The organic layer was separated, washed, dried, and evaporated and the residue was chromato- graphed on silica gel (SiO,). The first fraction eluted with benzene-EtOAc (5 : 1) gave starting material (la) (378 mg, 35%). The second fraction eluted with benzene-EtOAc (5: 1) gave 4-hydroxybenzonitrile (3a) (52 mg, 573, whose i.r. spectrum was identical with that of an authentic sample.' The third fraction eluted with benzene-EtOAc (3: 1) afforded the qtanophosphate (2a) (1.49 g, 55%) as a pale brown oil; v,,,, (liquid) 2 220 (CN), 1 675 (CO), 1 625 (C=C), 1 280 (Pa), and 1 14&900 cm-I (P-0-C); S(CDC1,) 1.35 (6 H, t, J 8 Hz, OCH,Me), 4.15 (4 H, quint.J 8 Hz, OCH,Me), 6.40 and 7.10 (4 H, ABq, J 10 Hz, CHZH). (Found: M+, 271.0609. C, ,H,,N05P requires M, 271.0610). Diethyl 1-Cyano-2-methoxy-4-oxocyclohexa-2,5-dienyl Phosphate (2b).-A mixture of (lb)* (1.38 g, 10 mmol), DEPC ( 1.95 g, 12 mmol), and LiCN (0.1 g, 3 mmol) in THF (50 ml) was treated as described for the preparation of the cyanophosphate (2a)to give a brown oil, which was chromatographed on SiO,. The first fraction eluted with benzene-EtOAc (10: 1) gave starting material (lb) (193 mg, 14%).The second fraction eluted with benzene-EtOAc (5:1) gave 4-hydroxy-2-methoxybenzo-nitrile (3b) (30 mg, 2%), m.p. 147-149 "C, recrystallised from benzene-ligroin 156-157 "C); v,,,. (Nujol) 3 250 (OH) and 2 220 cm- ' (CN); 6 ([2H6]-DMso) 3.84 (3 H, s, OMe), 6.47 (1 H, dd, J 1.9 and 8 Hz, 5-H), 6.53 (1 H, d, J 1.9 Hz, 3-H), 7.49 (1 J. CHEM. SOC. PERKIN TRANS. I 1987 H, d, J 8 Hz, 6-H), and 10.65 (1 H, s, OH); m/z 149 (M'). The third fraction eluted with benzene-EtOAc (3: 1) afforded the cyanophosphate (2b) (2.17 g, 71%) as a pale brown oil; v,,,. (liquid) 2 220 (CN), 1 670 (CO), 1 630 (C=C), 1 280 (Pa), and 1 140-900 cm-' (P-0-C); G(CDCI,) 1.39 (6 H, m, OCH,Me), 3.92 (3 H, s, OMe), 4.20 (4 H, m, OCH,Me), 5.69 (1 H, d, J 1.9 Hz, 3-H), 6.42 (1 H, dd, J 1.9 and 9.9 Hz, 5-H), and 7.03 (1 H, d, J 9.9 Hz, 6-H) (Found: M+,301.0714.CltHI6No6P requires M+, 301.07 16). General Procedure for the Preparation of Biaryls (4a,b), (5a,b)(5a',b'), (6a,b), (7a,b) (8a,b), and (9a)(9a').-A mixture of compounds (2a,b) (1 mmol) and BF,=OEt, (3 mmol) in sub- strates [benzene, toluene, p-and m-xylenes (3 mmol)] as solvent (10 ml) or MeCN (for anisole and naphthalene) (10 ml) was heated at 80-90 "C. After dilution with EtOAc (50 ml), the solution was washed, dried, and evaporated. The resultant biaryls were purified by chromatography on SiO, using benzene-EtOAc (20: 1) as eluant to give colourless crystals. 4-Hydroxy-3-phenylbenzonitrile(4a). The reaction time was 1 h; v,,,.(Nujol) 3 340 (OH), 2 210 (CN), and 1 600 cm-' (C=C); S(CDC1,) 5.80 (1 H, br s, OH), 7.07 (1 H, d, J9 Hz, 5-H), and 7.67.65 (7 H, m, ArH); m/z 195 (M+). 4-Hydroxy-3-(p-tolyI)benzonitrile(5a'). The crude product obtained by the general procedure (reaction time 1 h) from the cyanophosphate (2a) was purified by SiO, column chroma- tography with benzene-EtOAc (20:l) as eluant to give a colourless solid, which showed the presence of two components (5a) and (5a') in a ratio of ca. 3:7 in its 'H n.m.r. spectrum [S 2.10 and 2.40 (each s, Me)]. The mixture was again chromato- graphed on SiO, using benzene as an eluant to afford pure (5a') (45 mg); v,,,, (Nujol) 3 340 (OH), 2 220 (CN), and 1 595 cm-' (C=C); G(CDCI,) 2.40 (3 H, s, 4'-Me), 6.10 (1 H, s, OH), 7.0 (1 H, d, J8 Hz, 5-H), 7.35-7.4 (5 H, m, ArH), and 7.45 (1 H, dd, J8 and 2.5 Hz, 6-H).3-(2,5-Dimetkylphenyl)-4-hydroxybenzonitrile (6a). The reaction time was 0.5 h; vmaX.(Nujol) 3 320 (OH), 2 210 (CN), and 1 600 cm-' (C=C); S(CDC1,) 2.09 (3 H, s, 2'-Me), 2.36 (3 H, s, 5'-Me), 4.05 (1 H, br s, OH), 7.0 (1 H, s, 6'-H), 7.05 (1 H, d, J 8.4 Hz, 5-H), 7.25 (2 H, m, 3'- and 4'-H), 7.40 (1 H, d, J 2 Hz, 2-H), and 7.60 (1 H, d, J 8.4 Hz, 6-H). 3-(2,4-DimethylphenyI)-4-hydroxybenzonitrile (7a). The reaction time was 0.5 h; v,,,. (Nujol) 3 330 (OH), 2 210 (CN), and 1 595 cm- ' (C=C); 6(CDCI,) 2.10 (3 H, s, 2'-Me), 2.38 (3 H, s, 4'-Me), 7.05-7.20 (4 H, m, ArH), 7.42 (1 H, d, J 2 Hz, 2-H), and 7.58 (1 H, d, J 8.4 Hz, 6-H). 4-Hydroxy-3-( 1-naphthyf)benzonitrile (8a).The reaction time was 1 h; vmaX.(Nujol) 3 260 (OH), 2 210 (CN), and 1 610 cm-' (C=C); G(CDCI3) 5-40 (1 H, S, OH), 7.18 (1 H, d, J 8.5 Hz, 5-H), 7.45-7.70 (6 H, m, ArH), and 8.0 (2 H, t, J 8.5 Hz, 2'- and 8'-H). 4-Hydro.~y-3-(4-metho~~yphenyI)be~~onitrile(9a'). The crude product obtained by the general procedure (reaction time 10 min) from the cyanophosphate (2a) was purified by SiO, column chromatography with benzene-EtOAc (20: 1) as eluant to give a colourless solid, which showed the presence of two components (9a) and (9a') in a ratio of 2:8 in its 'H n.m.r. spectrum [6 3.75 and 3.85 (each s, OMe)]. The mixture was again chromatographed on SiO, using benzene as an eluant to give pure (9a') (210 mg); v,,,.(Nujol) 3 320 (OH), 2 210 (CN), and 1 600 cm-' (CS); G(CDCI,) 3.85 (3 H, s, OMe), 6.05 (1 H, s, OH), 6.95 (1 H, d, J 8 Hz, 5-H), 7.10 (4 H, ABq, J 8.5 Hz, ArH), 7.15 (1 H, d, J 2 Hz, 2-H), and 7.45 (1 H, dd, J 2 and 8 Hz, 6-H); m/z225 (M+). 4-Hydrox~~-2-rnethoxy-5-phen~~lbenzonitrile(4b).The reaction time was 0.5 h; vmaX.(Nujol) 3 300 (OH), 2 205 (CN), and 1 608 cm-' (CS);S([2H6]-DMso) 3.88 (3 H, s, OMe), 6.71 (1 H, s, 3-H), 7.28-7.58 (6 H, m, ArH), and 10.89 (1 H, s, OH); m/z225 (M+). mother liquor was chromatographed on SiO,. The fraction eluted with benzene-EtOAc (1O:l)gave a further crop of product which was recrystallised from MeCN. 7-Methyl-6-oxobenzopyrano[3,4-b] indole-2-carbonitrile (15a). Yield,30%; m.p.270-272 "C; vmax.(KBr) 2 220 (CN) and 1 725cm-' (CO); 6([2H6]-DMso) 4.19 (3 H, s, NMe), and 7.41-8.85 (7 H, m, ArH); m/z 274 (M+)(Found: C, 74.35;H, 3.75;N, 10.15.C,,H,,N,O, requires C, 74.44;H, 3.68;N, 10.21 %). 3-Methoxy-7-methyl-6-oxobenzopyrano[3,4-b)indole-2-carbonitrile (15b).Yield, 15%; m.p. >300 "C; v,,,.. (KBr) 2 220 (CN) and 1720 cm-' (CO); S(C2H6]-DMS0) 4.02 (3 H, s, OMe), 4.20 (3H, s, NMe), 7.46 (1 H, s, 4-H), 7.20-8.69 (4 H, m, ArH), and 8.82 (1 H, s, 1-H); m/z 304 (M+)(Found: C, 70.1;H, 3.95;N, 9.10.C18H,,N,03~H20requires C, 70.21;H, 4.06; N, 9.10%). Reaction of the Cyanophosphates (2a) and (2b) with 2,5-Dimethylfuran.-A mixture of the compounds (2a,b) (3 mmol), 2,Sdimethylfuran (579mg, 6 mmol), and BF3=OEt2 (852mg,6 mmol) in MeCN (12 ml) was heated at 50 "C for 45 min.The solvent was removed under reduced pressure and the residue was diluted with EtOAc. The organic solution was washed, dried, evaporated and the residue was purified by column chromatography on SiO, eluted with benzene-EtOAc (15 :1). 2-Methyl-3-(2-oxopropyl)benzofuran-5-carbonitrile (22a). Yield, 34%; m.p. 133-1 35 "C (recrystallised from benzene- ligroin); v,,,. (KBr) 2 220 (CN) and 1 710cm-' (CO); S(['H6]- DMSO) 2.18and 2.2 1 (3H, s, 2-Me and/or COMe), 4.09 (2 H, s, CH2CO), 7.70-8.13 (3 H, m, ArH); m/z 213 (M+)(Found: C, 73.25;H, 5.20 N, 6.65.C, jH ,,NO2 requires C, 73.22;H, 5.20; N, 6.57%).6-Methoxy-2-methyl-3-(2-oxopropyl)benzofuran-5-carbo-nitrile (22b). Yield, 49%; m.p.154-156 "C (recrystallised from benzene-ligroin); v,,,. (KBr) 2 220 (CN) and 1 710cm-' (CO); S([2H6]-DMSO) 2.13 and 2.18 (3 H, s, 2-Me and/or COMe), 3.39(3H, s, OMe), 4.0(2 H, s, CH,CO), 7.42 (1 H, s, 6-H), and 7.98(1H, s, 4-H); m/z 243 (M+)(Found: C, 69.20;H, 5.4;N, 5.75. C 14H, ,NO3 requires C, 69.12;H, 5.39; N, 5.76%). Reaction of the Cyanophosphate(2a) with 2-Methyl-5-propyl- furan.-A mixture of the cyanophosphate (Za)(4.09g, 15.08 mmol), 2-methyl-5-propylfuran (3.74 g, 30.16 mmol), and BF3-OEt, (5.14g, 36.2 mmol) in MeCN (10ml) was heated at 50°C for 2.5 h. The solvent was removed under reduced J. CHEM. SOC. PERKIN TRANS. I 1987 pressure and the residue was diluted with EtOAc. The organic solution was washed, dried, evaporated and the residue was purified by column chromatography on SO, eluted with benzene-EtOAc (30: 1) to give a viscous oil (1.51g, 42%), which was found to be a mixture of the benzofurans (24) and (25) in a ratio of ca.1 :1 by 'H n.m.r.spectroscopy. These were partially separated bychromatographyonSi0, using benzeneasaneluant. 2-Methyl-3-(4-oxopentyl)benzofuran-5-carbonitrile (24). Colourless crystals; m.p. 78-80 "C (recrystallised from benzene-ligroin); v,,,. (Nujol) 2220 (CN) and 1720 cm-' (CO); G(CDC1,) 0.91 (3 H, t, J 7.3Hz, CH,Me), 1.65 (2 H, m, CH,Me), 2.21 (3 H, s, CMe), 2.50(2H, 5, J 7.3Hz, COCH,), 3.84(2H, s, CH,CO), 7.50 (2 H, m, 6-and 7-H), and 7.80 (1 H, s, 4-H); m/z 241 (M+,1279,170 (20), and 71 (100) (Found: C, 74.9; H, 6.25;N, 5.75.CI5Hl5NO, requires C, 74.66;H, 6.27;N, 5.81%).3-(2-Oxopropyl)-2-propylbenzo~blfuran-5-carbonitrile(25). Colourless oil; vmaX.(liquid) 2 220 (CN) and 1 720 cm-' (CO); G([2H,]-DMSO) 0.96(3 H, t, J 7.5Hz, CH,Me), 1.68(2 H, m, CH,Me), 2.25 (3 H, s, COMe), 2.61 (2 H, t, J 7.5 Hz, CH,CH,Me), 3.86 (2 H, s, CH,CO), 7.50 (2 H, m, 6-and 7-H), and 7.84 (1 H, s, 4-H);m/z 241 (M+,35%), 199 (65), and 43 (100) (Found: M+, 241.1102.C,,H,,NO, requires M, 241.1103). References 1 S. Harusawa, R. Yoneda, T. Kurihara, Y. Hamada, and T. Shioiri, Tetrahedron Lett., 1984, 25, 427. 2 D. A. Evans, J. M. Hoffman, and L. K. Truesdale, J. Am. Chem. SOC., 1973, 95, 5822; D. A. Evans, L. K. Truesdale, and G. L. Carroll, J. Chem. SOC., Chem. Commun., 1973, 55; D. A. Evans and R.Y. Wong, J. Org. Chem., 1977, 42, 350. 3 S. Harusawa, M. Miki, J. Hirai, and T. Kurihara, Chem. Pharm. Buff., 1985, 33, 899. 4 C. S. Rondestvedt, Jr., Org. React., 1960, 11, 189. 5 E. N. Ugochukwu and R. L. Wain, Chem. Ind., 1965, 35. 6 T. Kurihara, M.Miki, R.Yoneda, and S. Harusawa, Chem. Pharm. Bull., 1986, 34,2747; T. Kurihara, M. Miki, K. Santo, S. Harusawa, and R. Yoneda, ibid., 1986, 34, 4620. 7 C. J. Pouchert, 'Aldrich Library of Infrared Spectra,' 2nd Ed., C9400-4. 8 C. D. Logan, R. M. Husband, and C. B. Purves, Can. J. Chem., 1955, 33, 82. 9 E.Spath and K. Klager, Chem. Ber., 1934, 67, 859. Received 18th July 1986; Paper 6/1430

ISSN:1472-7781    

DOI:10.1039/P19870001771

出版商:RSC    

年代:1987

数据来源: RSC