Ring opening of cyclic thioimidates in reaction with active methylene compounds

The reaction of cyclic thioimidates with active methylene compounds in the presence of acetic acid anhydride was studied. In case of six- and seven-membered derivatives the reaction proceeded via substitution of thiomethoxy group affording cyclic enamines. In case of five-membered derivatives the reaction proceeded via opening of the thioimidate ring affording functionalized aminopropane derivatives.