Lipase-catalyzed kinetic resolution of racemic 1-heteroarylethanols—experimental and QM/MM study
作者:Monica Toşa、Sarolta Pilbák、Paula Moldovan、Csaba Paizs、Gábor Szatzker、György Szakács、Lajos Novák、Florin-Dan Irimie、László Poppe
DOI:10.1016/j.tetasy.2008.07.004
日期:2008.8
The kinetic resolution of racemic 1-(benzothiazol-2-yl)ethanol rac-2a, 1-(benzo[b]thiophen-2-yl)ethanol rac-2b, 1 -(benzo[b]furan-3-yl)ethanol rac-2c and 1-(benzo[b]thiophen-3-yl)ethanol rac-2d was studied by enantiomer selective acylation catalyzed by a selection of commercially available and in house produced lipases. Alcoholysis of the Corresponding racemic acetates rac-3a-d catalyzed by Candida antarctica lipase B (CaLB) was also investigated. Two racemic 1-heteroarylethanols rac-2a,b were prepared by addition of the corresponding lithiated heteroarylic compounds la,b to acetaldehyde, whereas two others, rac-2c,d were synthesized by the addition of MeMgl onto the corresponding heteroaryl-carbaldehydes 1c,d. The high enantiomer selectivities of CaLB in the acylation of racemic 1-heteroarylethanols rac-2a-d allowed the determination of the enantiomeric preference of these enzymatic acetylation reactions by QM/MM [pm3/uff or hf(3-21+g**)/uff] calculations. For acetylation of each of the racemic alcohols rac-2a-d, four possible tetrahedral intermediate states were Compared and analyzed. (C) 2008 Elsevier Ltd. All rights reserved.