SYNTHESIS OF THE FIRST C3 RIBOSYLATED IMIDAZO[1,2-A]PYRIDINE C-NUCLEOSIDE BY ENANTIOSELECTIVE CONSTRUCTION OF THE RIBOSE MOIETY

The metabolic instability of the glycosidic linkage in ,6-trichloro-1- (beta-D-ribofuranosyl)benzimidazole prompted us to synthesize the stru cturally related C-nucleoside ro-3-(beta-D-ribofuranosyl)imidazo[1,2-a ]pyridine. Synthesis of this first C3-ribofuranosylimidazo[1,2-a]pyrid ine was accomplished by developing a modification of existing iodocycl ization methodology for obtaining a 1',4'-syn furanosyl precursor, wit hout an extensive protection scheme. This 1',4'-syn precursor was elab orated inter the desired ribofuranosyl C-nucleoside. X-ray crystallogr aphy was used to unambiguously determine structure and absolute stereo chemistry of this C-nucleoside.