Cycloaddition between electron deficient partners: an efficient regio- and stereoselective synthesis of functionalised bicyclo[2.2.2]octenones. A tandem alkylation, stereochemical inversion and aldol condensation

A novel one step regioand stereoselective synthesis of functionalised bicyclo[2.2.2]octenones from readily available aromatic precursors is described. The methodology involved in situ generation of reactive spiroepoxycyclohexadienones and p4sþp2s cycloaddition with methyl vinyl ketone. Study on p-facial alkylation that led to the formation of homobrendane derivatives as a result of stereochemical inversion and aldol condensation in tandem, is also presented. The crystal structure of 6-acetyl-1-methoxy-bicyclo[2.2.2]oct-7-en-2-onespiro[3,20]oxirane and 3-methoxy-4,6,9-trimethyltricyclo[4.3.1.03,7]decan-8-en-5-one-spiro[2,20]oxirane is also reported.