Patent ID: 7858774

Claim:
A method of preparing 5-azacytidine comprising the steps of: a) reacting 5-azacytosine with at least one silylating reagent to yield a silylated 5-azacytosine having the structure: wherein each R 1 is an optionally substituted C 1 -C 20 alkyl group independently selected from the group consisting of straight chain alkyl groups, branched alkyl groups, and cyclic alkyl groups; b) isolating the silylated 5-azacytosine by removing the silylating reagent using vacuum distillation or by filtration; c) coupling the isolated silylated 5-azacytosine with a compound of the structure: wherein the coupling is carried out in the presence of trimethylsilyl trifluoromethanesulfonate (TMS-Triflate) in at least one dry organic solvent; d) quenching the reaction mixture of Step c) with an aqueous quenching composition comprising a bicarbonate salt and extracting the quenched reaction mixture; e) replacing substantially all of the solvent in the extract of Step d) with methanol; f) deprotecting the product in the extract of Step d) with sodium methoxide in methanol to yield 5-azacytidine; and g) recrystallizing the 5-azacytidine product of Step f) from hot dimethylsulfoxide.