Lipase-catalyzed enantioselective transesterification of prochiral 1-((1,3-dihydroxypropan-2-yloxy)methyl)-5,6,7,8-tetrahydroquinazoline-2,4(1H,3H)-dione in ionic liquids.

The application of ionic liquids as solvents for transesterification of prochiral pirymidine acyclonucleoside using lipase (EC 3.1.1.3) Amano PS from Burkholderia cepacia (BCL) is reported. The effect of using medium reaction, acyl group donor, and temperature on the activity and enantioselectivity of BCL was studied. From the investigated ionic solvents, the hydrophobic ionic liquid [BMIM]PF6 ] was the preferred medium for enzymatic reactions. However, the best result was obtained in the mixture [BMIM][PF6 ]:TBME (1:1 v/v) at 50°C. Enzyme activity and selectivity in [BMIM][PF6 ]:TBME (1:1 v/v) was slightly higher in than in conventional organic solvents (for example, TBME), and in this condition, good activity and enantioselectivity were associated with unique properties of ionic liquid such as hydrophobicity and high polarity. Independently of solvents, monester of (R)-configuration was obtained in excess. Under optimal conditions, desymmetrization of the prochiral compound using different acyl donors was performed. If vinyl butyrate was used as the acylating agent, BCL completely selectively acylated enantiotopic hydroxyl groups.