Enzymatic reactions for the preparation of homocalycotomine enantiomers
摘要:
Homocalycotomine enantiomers (R)-4 and (S)-4 were prepared by the Candida antarctica lipase B (CAL-B)-catalysed asymmetric O-acylation of N-Boc-protected 2-(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolin-1-yl)ethanol (+/-)-1. The preliminary small-scale experiments were performed either in a continuous-flow system or as batch reactions, while the preparative-scale resolution was carried out in two steps with vinyl acetate as the acyl donor in the presence of Et3N and Na2SO4 in toluene at 3 C, as a batch reaction. Treatment of the resulting amino alcohol (S)-1 and amino ester (R)-3 (ee >= 94%) with 18% HCl, and then with 5 M NaOH, furnished the desired (R)-4 and (S)-4 without a decrease in the enantiomeric excess (ee >= 94%). (C) 2013 Elsevier Ltd. All rights reserved.
Enzymatic reactions for the preparation of homocalycotomine enantiomers
作者:László Schönstein、Enikő Forró、Ferenc Fülöp
DOI:10.1016/j.tetasy.2013.07.025
日期:2013.9
Homocalycotomine enantiomers (R)-4 and (S)-4 were prepared by the Candida antarctica lipase B (CAL-B)-catalysed asymmetric O-acylation of N-Boc-protected 2-(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolin-1-yl)ethanol (+/-)-1. The preliminary small-scale experiments were performed either in a continuous-flow system or as batch reactions, while the preparative-scale resolution was carried out in two steps with vinyl acetate as the acyl donor in the presence of Et3N and Na2SO4 in toluene at 3 C, as a batch reaction. Treatment of the resulting amino alcohol (S)-1 and amino ester (R)-3 (ee >= 94%) with 18% HCl, and then with 5 M NaOH, furnished the desired (R)-4 and (S)-4 without a decrease in the enantiomeric excess (ee >= 94%). (C) 2013 Elsevier Ltd. All rights reserved.