engleski

FUNCTIONALIZATION OF THE BICYCLO[3.2.1]-OCTADIENE SKELETON VIA PHOTOCATALYTIC OXYGENATION OF A (BENZO)FURAN DERIVATIVE

A simple and efficient protocol is utilized for the synthesis of novel functionalized benzobicyclo[3.2.1]octadiene derivatives by photocatalytic oxygenation of a furan derivative using an kationic and anionic free-base porphyrins as well as cationic and anionic manganese(III) porphyrins under different reaction conditions. The course and yields of these reactions were compared to those of the thermal reaction using m-chloroperbenzoic acid as the oxidizing agent. The deviating reaction pathways with anionic and cationic metalloporphyrins may be attributed to simultaneous electronic and steric effects. Application of free-base and metalated watersoluble porphyrins for photocatalytic oxygenation of the furan ring fused to the rigid methano-bridged skeleton proved to be regioselective and flexible compared to the thermal reactions with mCPBA, giving at the same time novel potentially biologically active bicyclo[3.2.1]octenes with the basic skeleton of which is incorporated in many natural compounds. Annulation of a benzene to the outer side of the furan ring, however, led to the formation of only one type of product, independently of the photocatalyst used. Different oxygenation mechanisms leading to the same end-product, the 10-membered keto-lactone derivative, have been suggested for the metalloporphyrins and the corresponding free bases.

Photocatalytic oxygenation; Porphyrins; Benzobicyclo[3.2.1]octadienes; (Benzo)furan derivative

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