A facile synthesis of 9-(1,3-dihydroxy-2-propoxymethyl) guanine (ganciclovir) from guanosine

The potent and selective antiviral drug ganciclovir (6) has been synthesize d in two steps via transpurination of fully acelylated guanosine (1) in the presence of 1,3-diacetoxy-2-(acetoxymethoxy)propane (2), followed by deace tylation in aqueous ammonia. The transpurination reaction also provides val uable side products, tetra-0-acetyl-beta-D-ribofuranose (5) and the 7-regio isomer of triacetylganciclovir (4); the latter product can be converted to the desired 9-isomer in a thermal 7 reversible arrow 9 isomerization.