Stereoselective Synthesis of Bicyclo[4.2.1]nonanes – a Temporary‐Bridge Approach to Cyclooctanoids

Abstract

Abstract 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.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)