Asymmetric desymmetrization of meso-pyrrolidine derivatives by enantiotopic selective C-H hydroxylation using (salen)manganese(III) complexes

Chiral (salen)manganese(III) complexes 1 catalyzed the asymmetric desymmetr ization of N-protected meso-pyrrolidine derivatives 3, 6-8, 15 and 18 by en antiotopic selective C-H oxidation in the presence of terminal oxidant iodo sylbenzene. The oxidation occurred chemoselectively at the carbon alpha to the nitrogen atom to afford optically active hydroxypyrrolidine derivatives 9, 11, 13, 16, 19 and 21 that were further oxidized to chiral lactams with Jones reagent. The N-protecting groups of the meso-pyrrolidine derivatives have notable effect on the enantioselectivity. (C) 1999 Elsevier Science L td. All rights reserved.