Highly functionalized glyco-conjugated hexahydroazepindiones from saccharide imides via the Norrish type II reaction

Starting from readily available protected 6-tosylates of d-glucose and d-mannose in both their pyranoside and furanoside forms as well as 6-tosylates of α-d-galactopyranose, the corresponding primary succinimido derivatives were obtained in good yield by nucleophilic displacement with potassium succinimide. These imido sugars were photochemically transformed into hexahydroazepindione derivatives such as by means of a Norrish type II reaction. As expected, the intramolecular alkylation proceeded via an 1,6 H-abstraction leading to a stabilized diradical. The regiochemistry of the photoreaction was controlled by configurational, conformational and electronic features and was sometimes influenced by the protecting groups. Using this route, a facile approach to a novel class of highly functionalized sugar derived heterocycles was developed.

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