Syntheses of imido-substituted glycosans and their photocyclisation towards highly functionalised heterotricycles Original Research Article

Reaction of O-protected amino-1,6-anhydro-β-d-hexopyranoses with succinic or glutaric anhydride and subsequent intramolecular acylation afforded the succinimido- and glutarimido-substituted glycosans. Irradiation with UV light of 254 nm wavelength led to γ-hydrogen abstraction at the pyranose ring by the excited carbonyl function. The stereoselective recombination of the resulting 1,4-diradicals gave annelated azetidinols, which fragmented by a retrotransannular ring opening reaction to give the glycosan-annelated azepanedione and azocanedione systems, respectively.