Highly enantioselective aldol reactions using a tropos dibenz[c,e]azepine organocatalyst
作者:Barry Lygo、Christopher Davison、Timothy Evans、James A.R. Gilks、John Leonard、Claude-Eric Roy
DOI:10.1016/j.tet.2011.09.101
日期:2011.12
The four-step synthesis of a chiral primary tertiary diamine salt, possessing a tropos dibenz[c,e]azepine ring is described. It is shown that 3.5–5 mol % of this salt is capable of promoting highly enantioselective crossed-aldol reactions between cyclohexanone and a series of aromatic aldehydes. In all cases, the aldol reactions proceed with high diastereoselectivity for the anti-aldol product. The
Solid acid–chiral amine hybrids have been synthesized and explored as recyclable and reusable enamine-type asymmetriccatalysts. Simple chiralamine–polyoxometalate (CA–POM) hybrids were identified as the optimal catalysts to promote a range of enamine-based transformations with high activity and excellent stereoselectivity under either neat or aqueousconditions. A catalyst loading as low as 0.33 mol-%