A New Sulfenylation Reagent, 3-Phenylsulfenyl-2-(N-cyanoimino)thiazolidine, and Its Optically Active Version

We have developed a new sulfenylation reagent, 3-phenylsulfenyl-2-(N-cyanoimino)thiazolidine 3, that is readily available and stable upon storage. Compound 3 easily reacts with amines or thiols to give the corresponding sulfenamides or asymmetrical disulfides in excellent yields. It was also found that the α-sulfenylation reaction of carbonyl compounds with 3 proceeds smoothly. Furthermore, optically active 4-diphenylmethyl derivative 4 was synthesized as an asymmetric sulfenylation reagent, which realized 96% e.e. upon α-sulfenylation of a cyclic β-keto ester.