Treatment of 6-deoxy-6-chloroganciclovir (I) with trimethylamine in DMF-THF at low temperature produced the trimethylammonium salt (II), which was subsequently displaced with KF in DMF at 80 C under vacuum removal of the Me3N to afford the corresponding 6-fluoro derivative (III). Finally, monoacylation with one equivalent of isobutyric anhydride (IV) in the presence of DMAP provided the target ester.