Patent ID: 7038038

Claim:
A method for preparing 5-azacytidine comprising the steps of: a) reacting 5-azacytosine with at least one silylating reagent to yield silylated 5-azacytosine; b) cooling the reaction mixture of step a) wherein solid silylated 5-azacytosine is formed; c) collecting said solid silylated 5-azacytosine by filtration; d) coupling the solid silylated 5-azacytosine of step c) with protected β-D-ribofuranose in a solvent having low water solubility, wherein the coupling is performed in the presence of a non-metallic Lewis acid catalyst; e) quenching the reaction mixture of step d) with a quenching composition comprising carbonate and bicarbonate salts and extracting the quenched reaction mixture with said solvent having low water solubility; f) replacing substantially all of the solvent in the extract with an alcohol; and g) deprotecting and desilylating the product of step d) by adding an alkoxide to the mixture of step f).