An Easy Deoxygenation of Conjugated Epoxides

An easy and high yielding transformation of epoxyketones and phenyl substituted epoxides to trans olefins in a convergent diastereoselective process is reported. The method was applied to the selective C-25 hydroxy-functionalisation of 3-keto-Δ4-cholestan-3-one, a key intermediate for the synthesis of C-25 hydroxy vitamin D3.