Stereoselective Synthesis of Bicyclo[4.2.1]nonanes: a Temporary-Bridge Approach to Cyclooctanoids
Résumé
A series of cis-α,γ-difunctionalized five-membered cyclic β- oxo esters have been chemo-, regio- and diastereoselectively prepared through an efficient domino anionic ring-cleavage/ ring-reconstitution/alkylation sequence including a 1,3-shift of the ester group. These unsaturated substrates were successfully engaged in various ring-closing metatheses to provide a reliable access to functionalized bicyclo[4.2.1]- nonanes, precursors of cyclooctanoids following the selective fragmentation of the one-carbon bridge.