A readily available, low cost bifunctional organic catalyst promoted the addition of nitroesters to imines; in the reaction between 2-nitropropionates and N-Boc protected aldehyde-imines the product bearing a new quaternarystereocenter was obtained in up to 81% ee. The positively charged catalyst was postulated to control the attack of the enolic form of nitroester to imine through a hydrogen bonding
Discovery of Bifunctional Thiourea/Secondary-Amine Organocatalysts for the Highly Stereoselective Nitro-Mannich Reaction of α-Substituted Nitroacetates
Asymmetric aza-Henry reaction with α-substituted nitroacetates catalyzed by a bifunctional thiourea-guanidine catalyst
作者:Bo Han、Wei Huang、Zhen Rui Xu、Xiao Ping Dong
DOI:10.1016/j.cclet.2011.01.038
日期:2011.8
The asymmetric aza-Henry reaction of a-substituted nitroacetates and N-Boc imines was achieved with a new-type thiourea-guanidine bifunctional organocatalyst. The novel transformations exhibited high diastereoselectivities, and the adducts bearing adjacent quaternary and tertiary chiral centers were generally obtained in moderate to good enantioselectivities (up to 88% ee). (C) 2011 Wei Huang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.