Improved preparation and structural investigation of 4-aryl-4-oxo-2-hydroxy-2-butenoic acids and methyl esters
摘要:
A simple and efficient oxalylation of aryl methyl ketones was accomplished with dimethyl oxalate in the presence of sodium methoxide. The unpreviously reported sodium ketoenolate esters were isolated and gently hydrolyzed into the ketoenol esters in good yields. Alternatively the sodium ketoenolate esters hydrolysis could also be conducted to directly afford the ketoenol acids, which represent one of the most promising class of HIV-1 integrase inhibitors. Advantages over previously reported procedures were better yields and simplicity of the purification protocol. (C) 2004 Elsevier Ltd. All rights reserved.
Asymmetric Organocatalytic Cascade Michael/Hemiketalization/Retro-Aldol Reaction of 2-[(<i>E</i>)-2-Nitrovinyl]phenols with 2,4-Dioxo-4-arylbutanoates: A Convenient Access to Chiral α-Keto Esters
unprecedented organocatalyticenantioselective cascade Michael/hemiketalization/retro‐aldol reaction of 2‐[(E)‐2‐nitrovinyl]phenols and 2,4‐dioxo‐4‐arylbutanoates is described. With a bifunctional squaramide catalyst incorporating (1R,2R)‐1,2‐diphenylethane‐1,2‐diamine, the reactions afford products in 75–99% yields with 80–98% ee. This process provides an enantioselective pathway for the synthesis of chiral
unprecedented stereoselective synthetic approach to δ-oxoesters derivatives from readily available starting materials has been developed. This method, catalyzed by N-heterocyclic carbene, involves an annulation–deoxalation reaction of alkynyl aldehydes with 2,4-diketoesters and proceeds via the chiral α,β-unsaturated acylazolium intermediates. The annulation includes the in situ formation of dihydropyranones
Pimenova, E. V.; Andreichikov, Yu. S., Journal of Organic Chemistry USSR (English Translation), 1992, vol. 28, # 2.2, p. 302 - 315
作者:Pimenova, E. V.、Andreichikov, Yu. S.
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作者:V. V. Zalesov、S. S. Kataev、N. A. Pulina、N. V. Kovylyaeva
DOI:10.1023/a:1020343221719
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By treating 4-aryl-2,4-dioxobutanoic acids or their alkyl esters with diazomethane alkyl 4-aryl-2-methoxy-4-oxo-2-butenoates and 1-R-3-aroyl-4-methoxy-4-methoxycarbonyl-4,5-dihydropyrazoles were prepared. O-Alkyl derivatives and substituted pyrazoles were also obtained by reaction of 4-aryl-2,4-oxobutanoic acids aryl amides with diazomethane and diazoethane.
Nekrasov, D. D.; Shurov, S. N.; Ivanenko, O. I., Russian Journal of Organic Chemistry, 1994, vol. 30, # 1, p. 136 - 142
作者:Nekrasov, D. D.、Shurov, S. N.、Ivanenko, O. I.、Andreichikov, Yu. S.