In the presence of samarium diiodide and a proton source, δ-oxo-γ, γ-disubstituted-α, β- unsaturated esters of general formula R–CO–C (R′, R′)–CH CH–CO2Bn readily cyclise to trans-cyclopropanol products and/or lactones derived from the cis isomers. For R= aryl, good stereoselectivities (ca 90%) in favor of the alcohols are generally obtained while a mixture of alcohols and lactones is obtained with R= alkyl or H. For R= cyclopropyl, the ...
