A novel allylic hydroxylation of sterically hindered olefins by Fe-porphyrin-catalyzed mCPBA oxidation

Article abstract of DOI:10.1016/S0040-4039(99)01437-9

A novel allylic hydroxylation by mCPBA of triterpenes bearing sterically hindered olefin is catalyzed by Fe(PFPP)Cl. Oleanolic acid, ursolic acid, dihydrolanosterol and their derivatives are converted to the corresponding allylic alcohols by mCPBA-Fe(PFPP)Cl under mild conditions. In contrast, for common or electron-deficient olefins, mCPBA-Fe(PFPP)Cl is an efficient epoxidation system. The intermediacy of an Fe-oxo-porphyrin and subsequent hydrogen abstraction and recombination are proposed for the selective α-hydroxylation of triterpenes.