19317-90-9Relevant articles and documents
Chemical synthesis of 7α-hydroxycholest-4-en-3-one, a biomarker for irritable bowel syndrome and bile acid malabsorption
Offei, Samuel D.,Arman, Hadi D.,Yoshimoto, Francis K.
, (2019/07/31)
7α-Hydroxy-cholest-4-en-3-one is a biomarker for bile acid loss, irritable bowel syndrome, and other diseases associated with defective bile acid biosynthesis. Furthermore, 7α-hydroxy-cholest-4-en-3-one is the physiological substrate for cytochrome P450 8B1 (P450 8B1 or CYP8B1), the oxysterol 12α-hydroxylase enzyme implicated in obesity and cardiovascular health. We report the chemical synthesis of this physiologically important oxysterol beginning with cholesterol. The key feature of this synthesis involves a regioselective C3-allylic oxidation of a 3-desoxy-Δ4-7α-formate steroid precursor to form 7α-formyloxy-cholest-4-en-3-one, which was saponified to yield 7α-hydroxy-cholest-4-en-3-one.
MnO2/TBHP: A Versatile and User-Friendly Combination of Reagents for the Oxidation of Allylic and Benzylic Methylene Functional Groups
Serra, Stefano
, p. 6472 - 6478 (2015/10/19)
In the presence of activated MnO2, tert-butyl hydroperoxide (TBHP) in CH2Cl2 is able to oxidize the allylic and benzylic methylene groups of different classes of compounds. I describe a one-pot oxidation protocol based on two sequential steps. In the first step, carried out at low temperature, MnO2 catalyses the oxidation of the methylene group. This is followed by a second step where reaction temperature is increased, allowing MnO2 both to catalyse the decomposition of unreacted TBHP and to oxidize allylic alcohols that could possibly be formed. The proposed oxidation procedure is generally applicable, although its efficiency, regioselectivity, and chemoselectivity are strongly dependent on the structure of the substrate. A simple and user-friendly synthetic procedure for the oxidation of allylic and benzylic methylene groups to the corresponding conjugated carbonyl derivatives is described. The proposed oxidation protocol is based on the combined use of MnO2 and tert-butyl hydroperoxide, and is generally applicable.
Synthesis of 7-dehydrocholesterol through hexacarbonyl molybdenum catalyzed elimination reaction
Ur Rahman, Faiz,Tan, Tian Wei
experimental part, p. 247 - 254 (2012/05/05)
The efficiency of hexacarbonyl molybdenum catalyzed elimination reaction of the allylic acetates has been improved by the presence of O,N- bis(trimethylsilyl) acetamide in the reaction medium. The methodology is particularly well employed for the elimination of 7-acetoxycholesterol-3- acetate(cholestrol-3,7-diacetate) for which the resulting product obtained was exclusively 5,7-homoannular diene(7-dehydrocholesterol-3-acetate). Good yield is achieved (up to 70 %) while decreasing the side products formation and reducing the costs as compared to the previously used procedures. Hexacarbonyl molybdenum elimination reaction is greatly influenced by the reaction temperature, at low as well as at high temperature low yield of the homoannular diene product is separated while at moderate conditions of temperature high products formation is observed.
