From Dienophiles to Dienes: Catalysis by Polystyrene-Supported Triphenylphosphine with Pentane-2,4-dione as Co-Catalyst

Three 1,1-diethoxyalk-3-yn-2-ones underwent isomerization and gave only the corresponding (3E,5E)-alkadienones in 72–87% yield when subjected to polystyrene-supported triphenylphosphine at 60 °C using acetylacetone as a co-catalyst. As a first step to make the dienes electron richer, the diethoxyacetyl moiety was reduced with sodium borohydride under Luche conditions and afforded the corresponding alcohols, with a 92% yield in the best case.