A facile synthesis ofN-acyl-1,3-oxathiol-2-imines,7, is reported. It comprises the reaction ofO-alkyl acylcarbamothioates,4, with 2-chloroketones in the presence of alcoholic sodium alkoxide. The resultingO-alkyl-S-substituted-N-acylcarbonimidothiates,6, undergo cyclization with elimination of alcohol, spontaneously, or upon heating in boiling toluene to form7.