Selectivity enhancement of epoxide hydrolase catalyzed resolution of 2,2-disubstituted oxiranes by substrate modification

Abstract

A series of (±)-2,2-disubstituted oxiranes bearing an alkene or alkyne functional group were resolved by bacterial epoxide hydrolases with excellent selectivities. The presence of a carbon–carbon double or triple bond furnished a highly flexible system for substrate modification, which allowed the enantioselectivity to be tuned by rational substrate modification. Thus, a significant selectivity enhancement of more than a ten-fold increase of E-values was achieved by appropriate choice of the C–C multiple bond, i.e. by (i) choosing an alkene or alkyne moiety or by (ii) variation of the E/Z-configuration of olefinic substrates. The enantioenriched epoxides and vicinal diols thus obtained may be easily transformed into ω-functionalized building blocks containing a chiral fully substituted carbon atom by oxidative cleavage of the carbon–carbon multiple bond.