“…Methods for the preparation of 2-acylazetidines could be traced back to 1969 with the first synthesis reported by Cromwell, by cyclization of 2,4-dibromoketones with primary amines (Scheme 1, A) or the addition of organolithiums to azetidines carboxylic acids (Rodebaugh and Cromwell, 1969, 1971; Kulkarni and Cromwell, 1977; Arnould et al, 1980; Scheme 1, B). Selected examples, for the stereoselective synthesis of 2-acylazetidines, include the nucleophilic addition of aryllithiums (Couty and Prim, 2002) and Grignard reagents (Couty et al, 2011) to optically active 2-cyanoazetidines (Scheme 1, E) or the addition of Grignard reagents to enantiopure Weinreb amides prepared from methyl 1-phenylethylazetidine-2-carboxylates (Ma et al, 2007; Scheme 1, C). Recently, the synthesis of 2-acylazetidines, by a one-pot tetramethylguanidine/I 2 -mediated formal [2+2] cycloaddition reaction of α-amidomalonate with enones, has been reported by Miao and Sun (Miao et al, 2013; Scheme 1, F).…”