Chiral 8-substituted 10,10-dimethyl-5-pyridin-2-yl-6-aza-tricyclo [7.1.1.02,7]undeca-2(7),3,5-trien-8-ols as enantioselective catalysts in the addition of diethylzinc to substituted benzaldehydes

Chiral 8-substituted 10, 10-dimethyl-5-pyridin-2-yl-6-aza-tricyclo[7.1.1.0(2,7)] undeca-2(7),3,5-trien-8-ols were prepared from highly enantiopure (>97% ee) (1R)-(+)-alpha-pinene. The enantioselectivity was assessed in the addition of diethylzinc to substituted benzaldehydes to yield alcohols of the (S)-configuration, with an enantiomeric excess that typically ranges from 45 to 79%. Importantly, the electron-releasing substituents at the meta-position of the substituted benzaldehydes exhibited high enantioselectivity during alkylation using diethylzinc. (c) 2005 Elsevier B.V. All rights reserved.