Cytidine nucleosides II. Photochemical synthesis of 5-alkylcytidine nucleosides

5-Alkylcytidine nucleosides were synthesized via a photocoupling reaction. 5-Propylcytidine and 5-propyl-2-deoxycytidine have been prepared through the reduction of 5-(3-propenyl)cytidine and its 2'-deoxy derivative, which in turn were prepared by photoirradiation of cytidine or 2'-deoxycytidine in the presence of 3-iodopropene. 5-(2-Hydroxyethyl)cytidine and its derivatives were obtained from the reaction of cytidine or 2'-deoxycytidine with 2-iodoethanol. Trimethylsilyl derivatives of 5-iodocytidine and 5-iodo-2'-deoxycytidine, when treated with methyl acrylate, or acrylonitrile and the reaction product in each case subjected to catalytic hydrogenation, afforded 5-[2-(methoxycarbonyl)ethyl]cytidine and its 2-deoxycytidine analogue, and the corresponding 5-(2-cyanoethyl)nucleosides, respectively.