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-Delta(4)-cholestan-3-one, a key intermediate for the synthesis of C-25 hydroxy vitamin D-3. (C) 2000 Elsevier Science Ltd. All rights reserved.
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-Delta(4)-cholestan-3-one, a key intermediate for the synthesis of C-25 hydroxy vitamin D-3. (C) 2000 Elsevier Science Ltd. All rights reserved.