Conjugate addition of nitroalkanes to an acrylate equivalent. Stereocontrol at C-alpha of the nitro group through double catalytic activation

Org Lett. 2009 Sep 3;11(17):3826-9. doi: 10.1021/ol901351k.

Abstract

An unprecedented highly selective direct conjugate addition of prochiral nitroalkanes (R not equal H) to acrylate equivalents is described. The method employs a unique Lewis acid/Brønsted base/MS ternary catalytic system and affords products with dr up to 97/3. With beta-substituted (R' not equal H) acceptors unprecedented levels of anti/syn selectivity (>or=96/4) are attained. Adducts can be transformed into enantioenriched gamma-amino acids and derivatives, including aldehydes, ketones, lactams, and peptides, through simple protocols with full recovery of camphor auxiliary, the source of chiral information.