Regioselective reactions of 2,3-endo-epoxybicyclo[3.2.0]heptanone ethylene acetal involving organometallic reagents

Abstract

The preparation of (1′,α,2′α,4′α,6′α)-spiro{[1,3]dioxolan-2,7′-[3′]oxatricyclo[4.2.0.0^2′,4′]octane}(3) and its reaction with various organometallic reagents is described. Attack occurred at C-2 preferentially (selectivity 67–83%) due to the influence of the neighbouring cyclobutane ring on the relative energies of the transition states leading to epoxy-ring opening. The conformation of the bicyclo[3.2.0]heptane system in the products is discussed.