Selectivity enhancement of PPL-catalyzed resolution by enzyme fractionation and medium engineering: Syntheses of both enantiomers of tetrahydropyran-2-methanol

Abstract

(±)-Tetrahydropyran-2-methanol (1) was successfully resolved into both enantiomers on a preparative scale after optimization by hydrolysis of its butyrate ester (±)-3 to (R)-(-)-3 (ee ≤ 99%). The antipodal alcohol (S)-(+)-1 (ee ≤ 95%) was obtained after recycling of the moderately S-enriched 1 to the butyrate ester 3 and subsequent hydrolysis. A fourfold increase in enantioselectivity (E value = 24) was observed when hydrolysis was performed using one of the fractions. Tetrahydrofurfuryl alcohol (2) could not be resolved since the best selectivity attained was E = 3.1 from hydrolysis by the lipase B of Candida antarctica. Resolution by transesterification was Sound to be unsuitable for both compounds.