Asymmetric reduction of ketones by employing Rhodotorula sp. AS2.2241 and synthesis of the β-blocker (R)-nifenalol

A broad range of prochiral ketones were efficiently reduced to the corresponding optically active secondary alcohols using resting cells of Rhodotorula sp. AS2.2241. The microbial reduction system exhibited high activity and enantioselectivity in the reduction of various aromatic ketones and acetylpyridines (> 97% ee), but moderate to high enantioselectivity in the reduction of alpha- and beta-keto esters. (R)-Nifenalol, a beta-adrenergic blocker, was also synthesized using 2-bromo-1(R)-(4-nitrophenyl)ethanol (97% ee) which was prepared through the asymmetric reduction of 2-bromo-1-(4-nitrophenyl)ethanone employing Rhodotorula sp. AS2.2241. The simple preparation and the high activity of the biocatalyst turned this system into a versatile tool for organic synthesis. (c) 2006 Elsevier Ltd. All rights reserved.