PROCESS FOR MAKING 5-AZACYTOSINE NUCLEOSIDES AND THEIR DERIVATIVES

摘要

A process of efficiently synthesizing a 5-azacytosine nucleoside of formula I: (see formula I) wherein R1 is hydrogen, hydroxy or halogen; R2 is hydrogen or halogen, such as azacitidine and decitabine, comprises coupling a silylated 5-azacytosine with a protected D-ribofuranose in the presence of a less than one molar equivalent sulfonic acid catalyst with respect to the protected D-ribofuranose. This process is efficient and amenable to manufacturing scale synthesis. It also does not require an aqueous workup or addition of a large amount of catalyst."