Bicyclo[4.2.1]non-1-en-8-one; a novel anti-Bredt enone. Synthesis of non-enolisable β-diketones from oxo-acids

Abstract

Several cyclic β-diketones were prepared by acid-catalysed intramolecular cyclisation of appropriate oxo-acids. One of them, bicyclo[4.2.1]nonane-2,8-dione, was converted into the bridgehead enone named in the title. Some reactions of this compound are reported. Reaction of (5R*,6R*)-6-tosyloxyspiro[4,4]nonan-1-one with boiling collidine gave 1,2,3,5,6,7-hexahydroinden-4-one by elimination and rearrangement.