Properties and Reactions of Substituted 1,2-Thiazetidine 1,1-Dioxides: Synthesis of N-Substituted 4,4-dimethyl-1,2-thiazetidin-3-one 1,1-dioxides,and a new base-catalyzed rearrangement to thiazolidin-4-one 1,1-dioxides

Alkylation of 3-oxo-1,2-thiazetidine 1,1-dioxide 2 yields the N-alkylated 3-oxo-β-sultams 3a-i . Solvolysis with NaOH or NH₃ selectively opens the N? S bond forming the sulfonate carboxamides 4 and the sulfonamidocarboxamides 7 , respectively. Furthermore, the hitherto unknown compounds of type 5 are prepared, representing a strained four-membered ring with a diacylated, sulfonated N-atom. Depending upon the reaction conditions, 3b-d and 3g are rearranged by base-catalyzed reactions into the substituted 4-oxothiazolidine 1,1-dioxides 9 or 10. Structures are elucidated by spectroscopic methods, established by crystal-structure analyses, and a possible way of formation is proposed. Furthermore, some side reactions and transformations are reported.