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Comparative Behaviour of 2,6-Di-tert-butyl- and 2,3-Dichloro-5,6-dicyano-1,4-benzoquino...
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Comparative Behaviour of 2,6-Di-tert-butyl- and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone with Some Phosphorus Reagents
作者:
Wafaa M. Abdou,
期刊:
Journal of Chemical Research, Synopses
(RSC Available online 1998)
卷期:
Volume 0,
issue 1
页码: 28-29
ISSN:0308-2342
年代: 1998
DOI:10.1039/a704394e
出版商: RSC
数据来源: RSC
摘要:
O O Ph3P CHCOR + O C OH C O– C H COR COR H CHCOR Ph3P COR C ROC H 6a–d 1 8a–d 9a–d E-10a–d 6,8–10 a R = OMe; b R = OEt; c R = Me; d R = Ph –Ph3PO 6 –Ph3P O Cl Cl O NC NC O Cl Cl O– NC NC O Cl Cl OR NC NC O Cl Cl OH NC NC O Cl Cl OH NC NC OH Cl Cl OH NC NC P OR OR OR P OR OR P OR OR OR OH P(OR)2 O O P(OR)3 13 4 14 15 R = Me 18 14A 17a,b TAPO + A B +H2 O (RO)2P(O)H 16 13–17 a R = Me; b R = Et + –ROH 28 J. CHEM. RESEARCH (S), 1998 J. Chem. Research (S), 1998, 28–29 J. Chem. Research (M), 1998, 0327–0339 Comparative Behaviour of 2,6-Di-tert-butyl- and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone with Some Phosphorus Reagents Wafaa M.Abdou,*a Monier A. I. Salemb and Ashraf A. Sediekb aDepartment of Pesticide Chemistry, National Research Centre, Tahrir St., Dokki, Cairo, Egypt bDepartment of Chemistry, Ain Shams University, Cairo, Egypt 2,6-Di-tert-butyl-1,4-benzoquinone (1) reacts with phosphorus ylides to give alkyl 1-p-hydroxyarylfumarates (ca. 75%); triethyl/methyl phosphites react with 1 and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 4) on oxygen but triisopropyl phosphite reacts with 1 on oxygen and with 4 on carbon.In connection with previous investigations,1,3 we are continuing our study of the interaction of the p-quinones 2,6-di-tertbutyl- 1,4-benzoquinone (1) and 2,3-dichloro-5,6-dicyano- 1,4-benzoquinone (DDQ, 4) with some penta- and tri-valent phosphorus reagents. 1. Reactions of 2,6-Di-tert-butyl-1,4-benzoquinone (1) with Phosphorus Ylides 6a–d.·Treatment of the quinone 1 with 2 mol.equiv. of alkoxy- (6a,b) or b-oxo-alkylidenephosphoranes (6c,d) in dry toluene solution followed by chromatography of the product mixture afforded the corresponding substituted phenols 10a-d in ca. 75% yield (Scheme 1). The reaction of 6c,d with 1 requires a protonating reagent (benzoic acid). The phenols 10a–d were only obtained in the E-configuration and assigned the alkyl 1-p-hydroxyarylfumarate structure.Points in favour of this conclusion are (a) compounds 10 have sharp melting points and did not show any spectral evidence for isomerism; (b) it is generally accepted7–9 that the geometry of the double bond in intramolecular Wittig reaction is usually E; (c) other related examples3,4 of stabilizd ylide reactions with p-quinones lead to either E-stereoselectivity or complete E-stereospecificity in these condensations. Mechanistically, the initially formed p-quinone methane intermedites 8a–d give, by Michael addition of a second ylide species 6, the betaines 9 which eliminate triphenylphosphine to give E-10a–d. 2. Reactions of Quinones 1 and 4 with Trialkyl Phosphites. ·In dichloromethane solution, the products of the reaction of 4 with trimethyl phosphite 13a were the p-alkoxyaryl dialkyl phosphate 15a (18%), the p-hydroxyaryl dialkyl phosphate 17a (20%) and the hydroquinone 18 (45%) (Scheme 2). No methyl chloride or acetonitrile could be detected.The results with triethyl phosphite (13b) were similar, except that the parallel p-ethoxyaryl diethyl phosphate (15; R=Et) was not observed. However the phosphate 17b (28%) and 18 (55%) were isolated by fractional crystallization of the product mixture. These results can be explained via intial attack by phosphorus on oxygen in 4 to yield the phosphonium species 14 which in the case of 13a (R=Me) would allow group translocation, giving the alkyl ether of dialkyl p-hydroxyaryl phosphate 15 (Path A, Scheme 2).Conversely, partial hydrolysis of 14 (adversion water) results in the formation of 17a,b via with intermediate 14A (Path B). On the other hand, the formation of 18 can be explained in terms of the high redox potential of DDQ15a together with the strong reducing character of the tertiary phosphite reagents14 which would facilitate the reduction of 4 with water (unavoidable moisture) to give 18 along with trialkyl phosphate. That 17b and 18 are only formed from the reaction of 13b with 4 can be attributed to the high reduction potential of 13b as compared to its methyl analogue,2,16 which facilitates the other competing reaction (reduction of DDQ) with formation of 18 in a high yield (55%).Conversely, when 4 was allowed to react with triisopropyl phosphite (13c) under the same reaction conditions as used with 13a,b, the reaction went via a different pathway to give the benzoquinone–diisopropyl phosphoante derivative 20 and the hydroquinone monoisopropyl ether 21 in nearly equal amounts (135%) (Scheme 3).It is obvious that carbon attack takes palce in the latter reaction to give the alkoxyphosphonium salt 19, which is then dealkylated by the displaced chloride ion (Michaelis–Arbuzov reaction) to give 20. Meanwhile, initial reduction of DDQ 4 to 18 (see above) and *To receive any correspondence. Scheme 1 Scheme 2OR Cl Cl OH NC NC O Cl O– NC NC O P(OR)2 Cl O NC NC Cl P OR O OR R O 18 + 21 19 20 13c –RCl 4 + P(OR)3 13c c, R = Pri + O– O OR O OH OH HO O P(OR)2 O P(OR)3 P(OR)2 O 23a R = Me b R = Et 24 22a–c 25a–c (R as in 16) 1 P(OR)3 13a–c Path A Path B P(OR)2OH NaOR a R = Me b R = Et c R = Pri 16 J.CHEM. RESEARCH (S), 1998 29 further alkylation of the product with a second molecule of 13c affords the respective monoisopropyl ether 21. Next, the reaction of the trialkyl phosphites 13a–c with 2,6-di-tert-butyl-1,4-benzoquinone (1) was also investigated. The reaction of 1 with trimethyl and triethyl phosphites (13a,b) proceeded smoothly in boiling toluene (3 h) to give the corresponding ether phosphates 23a (72%) and 23b (80%), respectively.With 13c, the same reaction conditions afforded 25c (80%). Hydroquinone 24 was, however, formed in the three reactions (s8%) (Scheme 4). The formation of 25c instead of the parallel 23c is not unexpected in view of the bulky isopropyl group which would impede the Arbuzov reaction. The structures of 23a and 23b were assigned through elemental analysis and by IR, 1H and 31P NMR and mass spectroscopy, but the identity of the known18 compound 25c was established by mp, mixed mp and comparative IR and mass spectra with an authentic sample prepared by the action of diisopropyl phosphite on 1 in the presence of sodium alkoxide.18 Techniques used: Elemental analysis, mass spectrometry, IR, 1H and 31P NMR References: 24 Equations: 6 Schemes: 4 Received, 23rd June 1997; Accepted, 2nd October 1997 Paper E/7/04394E References cited in this synopsis 1 W.M. Abdou, Y. O. Elkhoshnieh and A. A. Kamel, J. Chem. Res., 1996, (S) 326; (M) 1841. 3 W. M. Abdou, M. A. I. Salem and A. A. Sediek, Tetrahedron, 1997, 53, 13 945. 4 H. J. Bestmann and H. J. Lang, Tetrahedron Lett., 1969, 457. 7 B. E. Maryanoff and A. R. Reitz, Chem. Rev., 1989, 89, 863. 8 J. Leonard and G. Ryan, Tetrahedron Lett., 1987, 28, 2525. 9 I. I. Cubero and M. T. P. Lopez-Espinosa, Carbohydr. Res., 1988, 173, 41. 14 G. M. Kosolapoff, Organophosphorus Compounds, Wiley, London, 1950, p. 188. 15 J. Marsh, Advanced Organic Chemistry, Reactions, Mechanisms and Structures, 3rd edn., Wiley, New York, 1985; (a) ch. 15 and 16. 17 D. B. Denney and A. D. Pendse, Phosphorus Sulfur Relat. Elem., 1978, 5, 249. 18 N. A. Mukmeneva, V. Kh. Kadyrova, V. V. Moskva and N. A. Moskva, Zh. Obshch. Khim., 1985, 55, 696 (Chem. Abstr., 1985, 103, 123597). Scheme 3 Scheme 4
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