Divergent Preparation of Fluoroalkylated Sulfilimine and Sulfilimino Iminium Salts

Abstract

Abstract We have successfully extended our previously described methodology for the preparation of trifluoromethyl N ‐acyl sulfilimines to the case of bromodifluoro‐ and dichlorofluoromethyl derivatives. Attempts to convert such N ‐acyl sulfilimines to free NH‐sulfilimines failed. However, a strategy based on the reaction of their direct ditriflyl ketal precursor with amines allows the isolation of either original sulfilimino iminium salts using secondary amines or of free NH‐sulfilimines using primary amines. The latter were further easily N ‐functionalized with electron‐withdrawing groups giving structures close to those of efficient perfluoroalkylating agents. Preliminary experiments showed that these new sulfilimine‐based compounds have poor perfluoroalkylating abilities, demonstrating that the sulfilimine function is not sufficiently activating for that purpose, contrary to sulfur(VI) reagents.