Perhydro-1,3-benzoxazines derived from (−)-8-aminomenthol as ligands for the catalytic enantioselective addition of diethylzinc to aldehydes

Abstract

The catalytic potency of a series of perhydro-1,3-benzoxazines prepared from (−)-8-aminomenthol was examined in the enantioselective addition of diethylzinc to aldehydes. When (2 R,3 S,3a S,4a R,6 R,8a S)-2-isopropyl-6,9,9-trimethyl-3-phenyldecahydro-4a H-pyrrolo[2,1- b][1,3]benzoxazin-3-ol 7b was used as a chiral ligand, 1-substituted propanols with an ( R)-configuration were obtained in high yields and enantiomeric excesses up to >99%. The catalyst can be recovered and used without any loss in its activity.