Synthesis and biological evaluation of phosphonopyrimidine and phosphonopurine ribonucleosides.

Treatment of lithiated 2', 3', 5'-tri-Ο-protected uridine and 6-chloropurine ribonucleoside with diethyl chlorophosphate, followed by deblocking (and amination) and hydrolysis, provided 5-and 6-phosphonouridine (IV and VII), and 8-phosphonoadenosine (Xb), respectively. The Arbuzov reaction of 2', 3', 5'-tri-Ο-protected 4-chloro-2 (1H) -pyrimidinone ribonucleoside and triethyl phosphite afforded the diethyl 4-phosphonate derivative (XII). Compounds IV, VII and Xb, and their respective diethyl esters (IIb and VIb) and monoethyl ester (Xa) were inactive in vitro as antiviral and cytostatic agents, but the diethyl 8-phosphonate derivative (IXb) of 6-chloro-9- (β-D-ribofuranosyl) purine (VIIIa) showed some antiviral and cytostatic activities, which were comparable in all respects to those of VIIIa.