Lipase-catalysed alkoxycarbonylation of thymidine: influence of the carbonate on the regioselectivity of the process

Serine-hydrolases are known to catalyse alkoxycarbonylation processes. In t he field of nucleoside chemistry they can be used to perform regioselective transformations at the carbohydrate frame. In this paper we present data r egarding the influence of the structure of the carbonate on the regioselect ivity of the alkoxycarbonylation of thymidine catalysed by Candida antarcti ca lipase. As expected, assuming the formation of an acyl-enzyme intermedia te, the structure of the leaving group portion of the carbonate has no effe ct, whereas the remaining alcoholic portion of the carbonate has a marked e ffect. (C) 1999 Elsevier Science B.V. All rights reserved.