CHIRAL TOLUENE-2, ALPHA-SULTAM AUXILIARIES - PREPARATION AND STRUCTURE OF ENANTIOMERICALLY PURE (R)-ETHYL-2 AND (S)-ETHYL-2,1'-SULTAM

Crystalline sultams (R)-2 or (S)-2 were selectively prepared from prochiral saccharine (3) in two steps (53% overall yield) via Ru-(R)-BINAP- or Ru-(S)-BINAP catalyzed asymmetric hydrogenation of imine 4. Alternatively, pure (R)-2 was synthesized (37% overall yield) from (R)-α-phenethylamine in 4-5 steps involving the ortho-sulfination 6 → 7 and the highly diastereoselective cyclization of sulfinic acid 7 to the sulfinamide 8. X-ray diffraction analyses of sulfinamide 8 and sultam (R)-2 are presented. © 1990.