N-Carbamate-assisted stereoselective synthesis of chiral vicinal amino sulfides

[reaction: see text] Simply mixing amino alcohol A and thiol in toluene and TFA provided the corresponding amino sulfide B in excellent chemical yield and diastereoselectivity. A double SN2 process initiated by O-5 participation of the neighboring N-carbamate group was advanced to explain the overall retention of configuration at the chiral benzylic center.