Enantioselective synthesis of 2-substituted 4-aminobutanoic acid (GABA) analogues via cyanomethylation of chiral enolates
作者:Shamim Azam、Alice A. D'Souza、Peter B. Wyatt
DOI:10.1039/p19960000621
日期:——
Cyanomethylation by bromoacetonitrile of sodium or lithium enolates derived from (4S,5R)-3-acyl-4-methyl-5-phenyl-1,3-oxazolidin-2-ones usually shows good stereoselectivity; although the reaction of 3-(3-carboxypropanoyl)oxazolidinone 5d is exceptionally unselective, the 3-(pent-4-enoyl)- and 3-(3,4-dimethoxyhydrocinnamoyl)oxazolidinones 5e and 5f are found to be effective synthetic equivalents of 5d. The cyanomethylation products can be converted into 2-substituted derivatives of 4-aminobutanoic acid (γ-aminobutyric acid, GABA) by the alkaline hydrolysis of the oxazolidinone chiral auxiliary followed by hydrogenation of the cyano group.
由溴乙腈对源自(4S,5R)-3-酰基-4-甲基-5-苯基-1,3-恶唑烷-2-酮的钠或锂烯醇盐进行的氰甲基化通常显示出良好的立体选择性;尽管3-(3-羧基丙酰)恶唑烷酮5d的反应特别不选择性,3-(戊-4-烯酰)和3-(3,4-二甲氧基氢桂皮酰)恶唑烷酮5e和5f被发现是5d的有效合成等价物。这些氰甲基化产物可以通过恶唑烷酮手性辅助剂的碱性水解,并随之对氰基进行氢化,转化为4-氨基丁酸(γ-氨基丁酸,GABA)的2-取代衍生物。