Electrophilic alpha-thiocyanation of chiral and achiral N-acyl imides. A convenient route to 5-substituted and 5,5-disubstituted 2,4-thiazolidinediones

Electrophilic alpha-thiocyanation of N-acyl carboximides using N-thiocyanatosuccinimide and hydrolytic cyclization of the adducts affords 5-substituted and 5,5-disubstituted 2,4-thiazolidinediones in good overall yields. Alpha-thiocyanation of chiral N-acyl carboximides proceeds with excellent diastereoselectivity, although partial racemization occurs during subsequent cyclization.