Enzymatic reactions for the preparation of homocalycotomine enantiomers |
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Authors: | László Schönstein Enikő Forró Ferenc Fülöp |
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Affiliation: | Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u 6, H-6720 Szeged, Hungary |
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Abstract: | 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%). |
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