SYNTHESIS OF N-(PURIN-6-YL)PYRIDIUM SALT AND ITS APPLICATION IN SYNTHESIS OF PURINENUCLEOSIDE

This paper describes an efficient approach to convert inosine into 6-a mino(3),6-methoxy(5); and 6-ethoxy(6) derivatives that requires only m ild conditions. The 2', 3', 5'-tri-O-acetylinosine(1), treated with 4- ClPhOPOCl2 agent in the presence of dry pyridine at room temperature f orms fluorescent N-[9-(2' 3' 5'-tri-O-acetyl-beta-D-ribofuranosyl)puri ne-6-yl] pyridinium chloride (2), When treated with amines such as met hylamine and piperidine in methanol at room temperature gave 6-amino-9 -(beta-D-2' 3' 5'-tri-O-acetyl-ribofuranosyl) purine(4). The deacetyla ted adenosine (3) was formed by using ammoria. Treatment of intermedia te 2 with Et3N or 2 mol.dm-3 NaOH in methanol or ethanol at room tempe rature yielded the corresponding 6-methoxy and 6-ethoxy purinenucleosi de derivatives. A plausibe mechanism of the reaction is proposed.