Synthetic Nucleosides and Nucleotides. XIX. Synthesis of 3'-Deoxycytidine 5'-Triphosphate and Related 3'-Deoxy-ribonucleotides from Cordycepin'

Abstract

The pyrimidine 3'-deoxyriboside 5'-triphosphates, pyrimidine counterparts of cordycepin 5'-triphosphate, (1) were conveniently synthesized from cordycepin as potential deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase inhibitors. For the synthesis of 3'-deoxycytidine, p-chlororobenzoylation of 1 followed by acetolysis afforded an anomeric mixture of 1-O-acetyl-2, 5-di-O-p-chlorobenzoyl-3-deoxy-D-ribofuranose (3) in good yield. Condensation of 2, 4-bis-trimethylsilyl-N₄-acylcytosine (4a, b) with 3 in the presence of stannic chloride gave fully acylated 3'-deoxycytidine (5) in excellent yield. The protecting group was removed to give 3'-deoxycytidine (6), which on phosphorylation gave 3'-deoxycytidine 5'-monophosphate (7), a key intermediate in the present study. Deamination of 7 with nitrous acid afforded 3'-deoxycytidine-5'-monophosphate (8). Additionally, 2, 4-bis-trimethylsilyloxy-5-methyl-or ethylpyrimidine (4c, d) was coupled with 3 in a similar manner to give fully acylated 5-methyl-(5c) or 5-ethyl-3'-deoxyuridine (5d). The 5'-monophosphates were converted to the corresponding 5'-triphosphates by the phosphoroimidazolidate method.