Photochemical Transformation of Levoglucosan Imides to Anhydrosugar-Annelated Azepanediones and Azocanediones
By reaction of O-protected 3-amino-1,6-anhydro-β-D-glucopyranose with succinic, glutaric, and tartaric anhydride, respectively, the corresponding 3-substituted succinimido, glutarimido, and tatarimido derivatives were obtained. Irradiation of the succinimido and glutarimido derivatives at 254 nm gave 1,4-diradical intermediates by γ-hydrogen abstraction (Norrish Type II reaction) which subsequently recombined (Yang cyclization) to form azetidinols. These in turn fragmented and led to azepanedione and azocanedione derivatives. In contrast, irradiation of the tartarimido derivative resulted in elimination and led to both isomeric enolethers.
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