New transformation methods of Δ14,15 bond applied to certain cephalostatin analogue

Abstract

An unusual chlorination method was applied to protect simultaneously both Δ14,15 bond and carbonyl group in an analogue of the cephalostatin 1 I (a tumor inhibitor marine natural product). This method based on unusual reaction between commercially undistilled dichloromethane and diacetoxy iodosobenzene to give an intermediate reacting then with the diketone II leading finally to 14β,15α- dichlorodiketone IV. In addition, selective epoxidation of the double bond in II using lithium metal in THF gave compound VIII in a fair yield. Both processes are environmentally friendly processes and the products IV and VIII undergo chemoselective carbonyl reduction in the unfunctionalized side.