Rationalising diastereoselection in the dynamic kinetic resolution of α-haloacyl imidazolidinones
作者:Stephen Caddick、Kerry Jenkins、Nigel Treweeke、Sara X. Candeias、Carlos A.M. Afonso
DOI:10.1016/s0040-4039(98)00175-0
日期:1998.4
A crossover from S(N)2 to general base catalysed nucleophilic substitution can account for the dichotomous diastereoselectivity observed in DKR reactions of alpha-haloacyl imidazolidinones. Aprotic nucleophiles (Nu(-)) react preferentially with the 5S*,2'R* diastereomer via an S(N)2 mechanism. Conversely, amines (R2NH) generally react preferentially with the 5S*,2'S* diastereomer. General base catalysis via a bifurcated hydrogen bonded assembly accounts for this anomalous stereoselectivity. (C) 1998 Elsevier Science Ltd. All rights reserved.