Studies on the preparation and exchange reactions of 5‐deuterated uracils

The mechanism of base catalyzed proton exchange at the 5‐position of uracil and its N ‐methylated derivatives has been studied. These reactions proceed by addition — elimination across the 5,6‐double bond when the 1‐nitrogen is substituted with a methyl group, or with anchimeric assistance of the N ‐1 anion if the 1‐position is unsubstituted. The base catalyzed hydrolyses of 1,3‐dimethyluracil and 3‐methyluracil also appear to proceed through hydrated intermediates. A facile method for an acid catalyzed preparation of 5‐deuterated uracils is described as well as a simple and accurate method for analysis of deuterium content.