Synthesis of N-bridgehead heterocycles from saccharide benzimidazoles

Treatment of d-arabino-tetritol-1-yl-benzimidazole with p-toluenesulfonyl chloride (1 mol equiv) in pyridine, afforded the N-bridgehead heterocycles, 2R,3R,4S-trihydroxy-1:2:3:4-tetrahydropyridino[1,2-a]benzimidazole. The structure of the latter compound was determined by acylation, 1H, and 13C NMR spectroscopy and mass spectrometry.