Ring-opening of N-tosyl aziridines by 2-lithiodithianes

The reaction of lithiated dithianes 6–8 and 15 and 16 with enantiopure N-sulfonylated aziridines 1 and 2 leads via regiospecific nucleophilic ring-opening to enantiopure N-tosyl 2-(2′-dithianyl) secondary amines in good to excellent yields. These compounds may be either desulfonylated or hydrolytically desulfurized to give the corresponding amines 21–24 or carbonyl compounds 25–27 and 28–30 in good yield. In the case of α-silaalkanones 31 and 32 produced by these reactions, oxidation furnishes enantiopure 3-tosylamino acids 33 and 34 in good yield.