Regioselective Oxyfunctionalization of Unactivated Carbons in Steroids by a Model of Cytochrome P-450: Osmiumporphyrin Complex/<i>tert</i>-Butyl Hydroperoxide System
tert-Butyl hydroperoxide catalyzed by (5,10,15,20-tetramesitylporphyrinate) osmium(II) carbonyl [Os(TMP)CO] complex was found to be a highly efficient versatile oxidant for C−H carbons in steroid substrates. When reacted with representative steroids with an estrane, pregnane, 5β-cholane, or 5α-cholestane structure, regioselective oxyfunctionalization and/or oxidative degradation occurred to give a
Oxyfunctionalization of unactivated methine carbon atoms with dimethyldioxirane (DMDO) is studied for various substituted steroids related to the 5β-cholane and 5α-cholestane series. A highly efficient, stereoselective, one-step remote oxidation of specific methine carbons is attained by DMDO oxidation under mild conditions to give a variety of novel mono- and dihydroxylated steroids. The reactivity and site selectivity
An Iminium Salt Organocatalyst for Selective Aliphatic C–H Hydroxylation
作者:Daoyong Wang、William G. Shuler、Conor J. Pierce、Michael K. Hilinski
DOI:10.1021/acs.orglett.6b01832
日期:2016.8.5
salt are presented. The method allows the selective organocatalytic hydroxylation of unactivated 3° C–H bonds at room temperature usinghydrogenperoxide as the terminal oxidant. Hydroxylation of an unactivated 2° C–H bond is also demonstrated. Furthermore, improved functional group compatibility over other catalytic methods is reported in the form of selectivity for aliphatic C–H hydroxylation over alcohol
By treatment with perfluoro-cis-2-n-butyl-3-n-propyloxaziridine 1a, 5 beta-steroids 2a-i (belonging to different classes, such as androstanes, cholestanes, pregnanes, and cholanic acids) have been hydroxylated in good yields and with complete site selectivity and stereoselectivity to corresponding 5 beta-hydroxy derivatives 3a-i independently from the presence of halide, ketone, carboxylic acid, and ester moieties on C-3, C-11, C-12, C-17, C-20, C-21, and C-24.