A New Laboratory Scale Synthesis for the Anticancer Drug 3′-C-Ethynylcytidine­

A new synthetic route for the preparation of larger quantities of the anticancer nucleoside analogue 3′-C-ethynylcytidine is described. Starting from cytidine which was orthogonally protected in three steps, the ketonucleoside analogue as the key intermediate was obtained through oxidation of the unprotected 3′-hydroxy group. Stereoselective addition of the trimethylsilyl-protected acetylide residue at the 3′-carbonyl group followed by a complete deprotection afforded 3′-C-ethynylcytidine in an overall yield of 24% in seven steps.