Analogs of AICA- and isoAICA ribosides and their methylated base counterparts.

A mild, convenient and efficient synthesis has been developed for imidazole -4-thiocarboxamide and imidazole-5-thiocarboxamide ribosides and the analog ous selenocarboxamides. This methodology, i.e., DMF saturated with H2S or H 2Se, also converts the corresponding N-methylated bases to the correspondin g amides. The imidazole-4(5)-selenocarboxamides were shown to be sensitive to base (pH 11) and were easily converted back to their cyano precursors. T he kinetics of these reactions were determined and they indicate that the C 5 amides were more reactive than their C4 analogs.