The stereoselective total synthesis of (−)-dihydrotetrabenazine

A highly stereoselective synthesis of (−)-dihydrotetrabenazine has been accomplished using (R)-tert-butanesulfinamide as a chiral source. The synthesis involves the allylation of chiral N-sulfinyl imine followed by ring closure of the resulting secondary amide with a tethered halide and the Evans-Aldol reaction as key steps.