Patent ID: 7160999

Claim:
A method for the resolution of a mixture of the enantiomers of 2-hydroxylmethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane (FTC), which has the structure comprising the steps of: (i) providing the mixture of the enantiomers as an 5′-O-acylated derivative of the structure wherein R is an acyl group; (ii) exposing the 5′-O-acylated derivative of 2-hydroxylmethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane to an enzyme selected from the group consisting of Amano PS-800 lipase and α-chymotrypsin under conditions that allow selective hydrolysis of the 5′-O-acyl group; and (iii) separating the 5′-O-hydrolyzed enantiomer from the 5′-O-unhydrolyzed enantiomer.