Synthesis, oxidation and dehydrogenation of cyclic N, O-and N, S-acetals. Part 1. Transformation of N, S-acetals: 3-acyl-1,3,4-thiadiazolines

Aldehyde and ketone thiosemicarbazones are synthesized and cyclized into 3-acyl-1,3,4-thiadiazolines under acylating conditions. Reactions of the 2-monosubstituted heterocycles with oxidizing and dehydrogenating agents (KMnO 4 or for the first time with CAN, DDQ, IBDA) lead to the formation of thiadiazoles. CAN oxidation of 2,2-disubstituted 3-acyl-1,3,4-thiadiazolines regenerates the parent ketones efficiently.