Lipase-catalyzed resolution of 2-dialkylaminomethylcyclanols. Comparative studies

摘要

Extensive lipase screening was performed in relation to the asymmetric acetylation of rac-2-dialkylaminomethylcyclanols (1-6). The lipase PS- and Novozym 435-catalysed resolutions of 1-6 with various vinyl esters were studied in different organic media. High enantioselectivity (E > 200) was observed when vinyl acetate was used as acylating agent and diethyl ether as solvent. The (1R,2R) enantiomers react preferentially in the case of the cis isomers, whereas the (1R,2S) enantiomers do so in the case of the trans counterparts. The enantioselective acetylation of the five-membered amino alcohols (1, 3 and 5) proceeded much more rapidly than that of the six-membered amino alcohols (2, 4 and 6). The reaction rates were also affected by the solvent and by the quantity of the enzyme.