Nemoto Tetsuhiro, Tosaki Shin-Ya, Ohshima Takashi, Shibasaki Masakatsu
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
Chirality. 2003 May 5;15(4):306-11. doi: 10.1002/chir.10205.
Catalytic asymmetric synthesis of alpha,beta-epoxy esters and alpha,beta-epoxy carboxylic acid derivatives is described. Catalytic asymmetric epoxidation of alpha,beta-unsaturated carboxylic acid imidazolides using La-BINOL-Ph(3)As=O complex gave the corresponding alpha,beta-epoxy peroxy tert-butyl esters, which were directly converted to the alpha,beta-epoxy methyl esters by adding methanol to the reaction. This catalytic system had broad generality for epoxidation of various substrates. With the use of 5-10 mol% of the catalyst, both beta-aryl and beta-alkyl-substituted-alpha,beta-epoxy methyl esters were obtained in up to 91% yield and in up to 93% enantiomeric excess. In addition, efficient transformations of alpha,beta-epoxy peroxy tert-butyl esters into the alpha,beta-epoxy amides, alpha,beta-epoxy aldehydes, and gamma,delta-epoxy beta-keto esters are also reported.
描述了α,β-环氧酯和α,β-环氧羧酸衍生物的催化不对称合成。使用La-BINOL-Ph(3)As=O配合物对α,β-不饱和羧酸咪唑酯进行催化不对称环氧化反应，得到相应的α,β-环氧过氧叔丁酯，通过向反应中加入甲醇可将其直接转化为α,β-环氧甲酯。该催化体系对各种底物的环氧化反应具有广泛的通用性。使用5-10 mol%的催化剂，β-芳基和β-烷基取代的α,β-环氧甲酯的产率高达91%，对映体过量高达93%。此外，还报道了α,β-环氧过氧叔丁酯高效转化为α,β-环氧酰胺、α,β-环氧醛和γ,δ-环氧β-酮酯的反应。
