A short synthesis of appropriately substituted 3,3-dichloroazetidines,
a virtually unknown class of azetidines, is described. The reaction o
f 3,3-dichloro-1-azaallylic carbanions, generated from N-(1-aryl-2,2-d
ichloroethylidene)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. Reacti
on of these alpha,alpha-dichloro-beta-(mesyloxy) ketimines with potass
ium cyanide or sodium borohydride in methanol furnished a variety of 2
-cyano- and 2-methoxy-3,3-dichloroazetidines in a stereoselective mann
er. Reduction of beta-(mesyloxy) imines with sodium cyanoborohydride f
ollowed cyclization with potassium carbonate in DMSO yielded 3,3-dichl
oroazetidines as well.