Efficient Asymmetric Synthesis of Unnatural β-Amino Acids
作者:Carsten Bolm、Ingo Schiffers、Christian L. Dinter、Laurent Defrère、Arne Gerlach、Gerhard Raabe
DOI:10.1055/s-2001-16745
日期:——
The simple and highly enantioselective methanolysis of cyclic meso-anhydrides mediated by cinchona alkaloids leads to a broad variety of dicarboxylic acid mono-methyl esters with up to 99% ee. From these products, unnatural N-protected β-amino esters can be obtained by means of Curtius degradation of the corresponding acyl azides. Subsequent cleavage of the protecting groups leads to the free β-amino acids in excellent yields. By enantiomer differentiating opening of racemic anhydrides, synthetically highly useful regioisomeric amino acid esters become readily available.
由金鸡纳生物碱介导的环状内消旋酸酐的简单且高度对映选择性的甲醇分解可产生多种二羧酸单甲酯,其 ee 高达 99%。从这些产品中,可以通过 Curtius 降解相应的酰基叠氮获得非天然的 N-保护的 β-氨基酯。随后保护基团的裂解导致游离β-氨基酸的产率极好。通过外消旋酸酐的对映异构体差异化打开,合成上非常有用的区域异构氨基酸酯变得容易获得。
The Diels-Alder Reactions of the Piperylene Isomers with Maleic Anhydride and Fumaric Acid
作者:David Craig
DOI:10.1021/ja01160a070
日期:1950.4
Use of an acetylenic sulfone as an alkene dipole equivalent in the synthesis of (±)-pumiliotoxin C
作者:Thomas G. Back、Katsumasa Nakajima
DOI:10.1016/s0040-4039(96)02506-3
日期:1997.2
yclohexanecarboxylate (3) with 1-p-(toluenesulfonyl)-1-pentyne (4) afforded the corresponding enaminone 2, that was in turn reduced to (±)-pumiliotoxin C (1). The acetylenic sulfone 4 thus functions as the synthetic equivalent of the alkene dipole 5 in this process.