19454-73-0Relevant academic research and scientific papers
A novel allylic hydroxylation of sterically hindered olefins by Fe-porphyrin-catalyzed mCPBA oxidation
Konoike, Toshiro,Araki, Yoshitaka,Kanda, Yasuhiko
, p. 6971 - 6974 (2007/10/03)
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.
Stereoselectivity in Reduction of Steroidal 7-Ketones
Maruyama, Sanae,Ogihara, Noriko,Adachi, Itsuko,Ohotawa, Junko,Morisaki, Masuo
, p. 1847 - 1852 (2007/10/02)
Several 7-ketones of lanostane, 4,4-dimethylcholestane and cholestane derivatives were subjected to catalytic hydrogenation on platinum, reduction with complex hydrides and reduction with sodium in tert-butanol, and the product ratios (7α-ol/7β-ol) were determined by gas chromatography or high-performance liquid chromatography.Catalytic hydrogenation of 3β hydroxylanostan-7-one and 3β-hydroxy-4,4-dimethylcholestan-7one yielded the 7β-alcohols as the major products, whereas their 3-acetates gave prinsipally the 7α-alcohols.Reductionof various 7-ketones with sodium in tert-butanol gave mainly the 7β-equitoiral alcohols, while the epimeric 7α-ols were the major products on reduction with litium tri-sec- butilborohydride.The stereoselectivity of reduction with sodium borohydride and lihium aluminium hydride was highly dependent on the neighboring double bond and 4,4-dimethiyl and/or 14α-methyl substituent(s). Keywords---reduction; 7-oxygenated sterol; stereoselectivity; lithium tri-sec-butylborohydride; 3β-hydroxy-4,4-dimethylcholestan-7one
