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

Abstract

Chiral (salen)manganese(III) complexes 1 catalyzed the asymmetric desymmetrization of N-protectedmeso-pyrrolidine derivatives 3, 6–8, 15 and 18 by enantiotopic selective C-H oxidation in the presence of terminal oxidant iodosylbenzene. The oxidation occurred chemoselectively at the carbon α 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.