Hydrothermal deamidation of 4-N-acylcytosine nucleoside derivatives: efficient synthesis of uracil nucleoside esters

[reaction: see text] N,O-Peracylated cytidine and 2'-deoxycytidine derivatives in superheated water/DME solutions (oil bath at 125 degrees C) undergo hydrolytic deamidation (and/or N-deacylation). Acylated starting materials derived from arylcarboxylic acids give the corresponding uridine esters cleanly, and such derivatives crystallize selectively from the cooled reaction mixtures in high yields.