Chemo- and diastereoselective control for a flexible approach to (5S,6S)-6-alkyl-5-benzyloxy-2-piperidinones
作者:Liang-Xian Liu、Kai-Jiong Xiao、Pei-Qiang Huang
DOI:10.1016/j.tet.2009.03.021
日期:2009.5
Chemo- and diastereoselective transformation of the N,O-acetals and their chain tautomers (4/5), readily derived from protected 3-hydroxyglutamide 1a, Was Studied. It Was Uncovered that while the reaction with a combination of boron trifluoride etherate/zinc borohydride led to cyclic products (5S,6S/R)-6-alkyl-5-benzyloxy-2-piperidinones 3/2, and 6 in modest chemo- and diastereoselectivities, the reaction of 4/5 with zinc borohydride led exclusively to the formation of the ring-opening products 6 in excellent anti-diastereoselectivities. On the basis of the latter reaction, a flexible approach to (5S,6S)-6-alkyl-5-benzyloxy-2-piperidinones 3 was disclosed. (C) 2009 Elsevier Ltd. All rights reserved.