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

(±)-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 found to be unsuitable for both compounds.