A convenient synthesis of 3,3-dichloroazetidines, a new class of azetidines

A short synthesis of appropriately substituted 3,3-dichloroazetidines, a virtually unknown class of azetidines, is described. The reaction of 3,3-dichloro-1-azaallylic carbanions, generated from N-(1-aryl-2,2-dichloroethylidene)amines, with aromatic aldehydes produced alpha,alpha-dichloro-beta-hydroxy imines that, upon treatment with mesyl chloride, were converted into the corresponding beta-(mesyloxy) imines. Reaction of these alpha,alpha-dichloro-beta-(mesyloxy) ketimines with potassium cyanide or sodium borohydride in methanol furnished a variety of 2-cyano- and 2-methoxy-3,3-dichloroazetidines in a stereoselective manner. Reduction of beta-(mesyloxy) imines with sodium cyanoborohydride followed cyclization with potassium carbonate in DMSO yielded 3,3-dichloroazetidines as well.