RATIONALIZING DIASTEREOSELECTION IN THE DYNAMIC KINETIC RESOLUTION OFALPHA-HALOACYL IMIDAZOLIDINONES

Authors
CADDICK S JENKINS K TREWEEKE N CANDEIAS SX AFONSO CAM
Citation
S. Caddick et al., RATIONALIZING DIASTEREOSELECTION IN THE DYNAMIC KINETIC RESOLUTION OFALPHA-HALOACYL IMIDAZOLIDINONES, Tetrahedron letters, 39(15), 1998, pp. 2203-2206
Citations number
15
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Tetrahedron letters → ACNP
ISSN journal
00404039
Volume
39
Issue
15
Year of publication
1998
Pages
2203 - 2206
Database
ISI
SICI code
0040-4039(1998)39:15<2203:RDITDK>2.0.ZU;2-C
Abstract
A crossover from S(N)2 to general base catalysed nucleophilic substitu tion 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 preferentiall y with the 5S,2'S* diastereomer. General base catalysis via a bifurca ted hydrogen bonded assembly accounts for this anomalous stereoselecti vity. (C) 1998 Elsevier Science Ltd. All rights reserved.