Nucleophilic acylation of α-haloketones with aldehydes: an umpolung strategy for the synthesis of 1,3-diketones

The first example of N-heterocyclic carbene (NHC)-promoted intermolecular acylation of alpha-haloketones with aldehydes and alpha,beta-unsaturated aldehydes (enals) is reported. The protocol involves carbonyl umpolung reactivity of aldehydes and enals in which the carbonyl carbon attacks nucleophilically on electrophilic terminal of alpha-haloketones to afford 1,3-diketones and alpha,beta-unsaturated 1,3-diketones, respectively. Short reaction time, ambient temperature, operational simplicity, and high yields are the salient features of the present procedure. (C) 2010 Elsevier Ltd. All rights reserved.