Synthesis of acyclic nucleosides using new coupling reagent

Abstract

It was found that cesium iodide, zinc iodide, and lithium bromide-trifluoroagetic acid were good alkylation agents at $N^1$ position of pyrimidine bases and $N^9$ position of purine bases. Reaction using lithium bromide-trifluoroacetic acid gave moderate yields and limited to the preparation of 2-thiopyrimidine acyclic nucleosides. Zinc iodide was found to be a good coupling reagent, particularly useful for the synthesis of 2-thiopyrimidine and purine acyclic nucleosides (35-85\%). The coupling reaction using zinc iodide was carried out in dimethylformamide. It was found that cesium iodide was an excellent alkylation reagent at $N^1$position of pyrimidine and $N^9$ position of purine bases in acetonitrile. 2-Thio, 2-oxopyrimidine, purine, adenine, and guanine were success fully synthesized in excellent yields. Acylic nucleoside and other C-nucleoside derivatives containing fluorine and chlorine atoms, and hydroxy functional groups were synthesized using cesium iodide catalyst in good yields.