Bridgehead Substitution via Putative Norborn-1-en-3-ones: Application in the Synthesis of Complex Molecules.

The base-mediated formation of a bridgehead double bond in a bicyclo[2.2.1]heptane system (anit-Bredt molecules) is described. The synthesis of exocyclic norbornyl enones by Wittig reaction of α-diketones is reported. These enones and their Michael adducts are used as substrates for the generation of transient bridgehead enones and their trapping with MeOH and H2 O. Bridgehead alcohols are easily synthesized from norbornyl enones and are exploited for the diversity oriented synthesis of frameworks of natural and unnatural products.

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes.

An unexpected reactivity of the superoxide ion leading to the synthesis of tetrachloroaryl/vinyl-substituted nortricyclenes through its dual mode of action has been reported. KO2 was found to be superior and the only reagent to perform this kind of reaction over other conventional bases. Addition of the antioxidant BHT (2,6-di-tert-butyl-4-methylphenol) improved the yields of methylenenortricyclenes. A complete deuterium incorporation was observed in the superoxide-mediated reaction in DMSO-d 6. Friedel-Crafts acylation reactions of 3-methylenenorticyclenes yielded 2-propanone-substituted pentachloronorbornenes.