A new entry to optically pure trans-2, 3-disubstituted N-sulfinyl aziridines starting from 1, 2- aminosulfides, involving formation of a sulfonium salt intermediate followed by intramolecular nucleophilic attack by the sulfinamide nitrogen atom, is reported. The regio- and stereoselective opening of the aziridine ring can be achieved by anchimeric assistance of the sulfinyl group.