Kinetic Resolution of 1-Biaryl- and 1-(Pyridylphenyl)alkan-1-ols Catalysed by the Lipase B from Candida antarctica
✍ Scribed by Robert Kourist; Javier González-Sabín; Ramón Liz; Francisca Rebolledo
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 126 KB
- Volume
- 347
- Category
- Article
- ISSN
- 1615-4150
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✦ Synopsis
Lipase B from Candida antarctica (CAL-B) catalyses the highly enantioselective (E > 200) transesterification of some 1-biaryl-2-yl-, -3-yl-, and -4-ylethanols and -propan-1-ols, as well as 1-(o-, m-, and p-pyridylphenyl)ethanols, 6, with vinyl acetate, Kazlauskas rule being obeyed in all cases. meta and para-Substituted substrates were transformed within several hours (conversion degree ranging from 23 -50%), reaction rates for propan-1-ol derivatives being slower than those for ethanol derivatives. Transesterifications of ortho-substituted alcohols took several days and were accompanied by a chemoenzymatic side reac-tion: the formation of another acetate derived from the hemiacetal between 6 and acetaldehyde coming from vinyl acetate. This side reaction was suppressed in the presence of isopropenyl acetate as acyl donor, conversion degrees for transesterification ranging from 20 -40% after ten days (E > 200). The usefulness of (R)-6p as ligand in the asymmetric addition of diethylzinc to benzaldehyde was also demonstrated.