Synthetic studies towards bridgehead diprenyl-substituted bicyclo[3.3.1]nonane-2,9-diones as models for polyprenylated acylphloroglucinol construction

The synthesis of bridgehead diprenylated bicyclo[3.3.1]-nonane-2,9-dione, based on a reductive rearrangement of an enol lactone, is presented. The same target could be reached by a one-step sequence involving Michael addition of 2,6-diprenylcyclohexanone onto acrolein and intramolecular aldol reaction. The first method could be extended to the for mation of a compound with gem-dimethyl substituents adjacent to the bridgehead position, but the construction of a suitably substituted enol lactone, with a view to polyprenylated acylphloroglucinol elaboration, could not be achieved. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)