N-sulfonylamidines. Part III. A new rearrangement reaction of N-alkylsulfonyl-amidines: Synthesis of enamines, β-aminosulfonyl-enamines and 4H-thiazete-S,S-dioxides

On reaction with lithium diisopropylamide, N-alkylsulfonylamidines (1) ( a new class of amidines) rearrange by intramolecular attack of the carbanion generated α to the SO2 group on the amidine carbon. Through a cyclic thiazetidine intermediate three main classes of compounds are formed, i.e. enamines (8), β-aminosulfonylenamines (9) and 4H-thiazete-S,S-dioxides (6). In the rearrangement products 8 and 9 the two carbon moieties of the amidine formerly linked to the N and S atoms, respectively, become linked together, with the formation of a new C-C bond.