Lewis Base Activation of Lewis Acids: Catalytic, Enantioselective Addition of Silyl Ketene Acetals to Aldehydes.

阅读量：

作者：

展开

摘要：

A catalytic system involving silicon tetrachloride and a chiral, Lewis basic bisphosphoramide catalyst is effective for the addition of glycolate-derived silyl ketene acetals to aldehydes. It was found that the sense of diastereoselectivity could be modulated by changing the size of the substituents on the silyl ketene acetals. In general, the trimethylsilyl ketene acetals derived from methyl glycolates with a large protecting group on the alpha-oxygen provide enantiomerically enriched alpha,beta-dihydroxy esters with high syn-diastereoselectivity, whereas the tert-butyldimethylsilyl ketene acetals derived from bulky esters of alpha-methoxyacetic acid provide enantiomerically enriched alpha,beta-dihydroxy esters with high anti-diastereoselecitvity.

展开

关键词：

hydroxycarboxylic acids (ether carboxylic acids) (acyclic compounds) and esters diastereoselective syntheses, enantioselective syntheses (incl. cis/trans‐isomerism

DOI：

10.1021/jo8006539

被引量：

621

年份：

2008