Electron-deficient benzotriazoles for the selective N-acetylation of nucleosides

The use of an acetylated benzotriazole for the selective protection of the amino groups of cytidine and 2′-deoxycytidine is reported. The use of the acetyl group is of considerable interest industrially in this role, and a single-step protection strategy advantageous in bulk production. 1-Acetyl-4-nitrobenzotriazole was found to readily acetylate the amine of cytidine preferentially over the exposed alcohol functionalities. With adaptation of the protocol, 2′-deoxycytidine was protected using the same reagent. A similar approach was attempted for the benzoylation of adenosine but was found to be unsuitable.