77059-25-7Relevant articles and documents
Oxysterols: Synthesis and anti-leishmanial activities
Ghosh, Pranab,Ghosh, Ashim,Mandal, Amitava,Sultana, Sirin Salma,Dey, Somaditya,Pal, Chiranjib
, p. 65 - 73 (2016/03/04)
Oxygenated sterols (2-16) were synthesized by skeletal rearrangement of steroidal allylic alcohols. All the derivatives were screened for their anti-leishmanial activities. Compounds 3, 11 and 12 showed potent activities. Compound 12 was found least toxic and induced highest nitric oxide (NO) at 48 h. Least toxicity of compound 12 on splenocytes validated its best anti-amastigote effect and induction of NO.
Selective reduction of α,β-unsaturated steroidal carbonyl compounds by NaBH4in presence of guanidine hydrochloride in dioxane
Khan, Salman Ahmad,Asiri, Abdullah M.
, p. 6331 - 6334 (2015/02/19)
A selective hydrogenation of α,β-unsaturated steroidal carbonyl compounds with NaBH4in the presence of guanidine hydrochloride in dioxane in good to excellent yields are described.
Synthesis of 7-dehydrocholesterol through hexacarbonyl molybdenum catalyzed elimination reaction
Ur Rahman, Faiz,Tan, Tian Wei
, 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.
On the Mechanism of Oxygenation of Olefins by Tetraphenylporphinatoiron(III)-Peroxide Systems
Muto, Toshiki,Masumori, Hiroaki,Miura, Toshiaki,Kimura, Michiya
, p. 2177 - 2183 (2007/10/02)
The mode of oxygenation by meso-tetraphenylporphinatoiron(III)-chloride (Fe(III)TPPCl)-peroxide systems was characterized by using cis-stilbene (1) and cholesteryl acetate (3) as substrates.The stereoselectivity of epoxidation of 1 by the Fe(III)TPPCl-tert-butyl hydroperoxide (tBuOOH) system depended on the concentration of Fe(III)TPPCl; the reaction was nonstereoselective at 0.1 mM Fe(III)TPPCl but stereoselective at 10 mM Fe(III)TPPCl.In the reaction of 3 with the same system, both allylic oxidation and epoxidation proceeded.However, the epoxidation was β-selective independently of the concentration of Fe(III)TPPCl.Thus, tBuOOH is assumed to decompose by a radical chain reaction mechanism to give tert-butylperoxyl radical (tBuOO.) and tert-butyloxyl radical (tBuO.) at 0.1 mM Fe(III)TPPCl.At 10 mM Fe(III)TPPCl, on the other hand, the O-O bond in the Fe(III)TPPCl-tBuOOH complex may cleave in both a homolytic manner (quasi-Fenton mechanism) and a heterolytic one (ferryl ion mechanism).The former leads to tBuO. as the active oxygen species responsible for the allylic oxidation of 3 and the latter to ferryl ion (Fe-O.) as that responsible for the stereoselective epoxidation of 1 and β-epoxidation of 3.In the reaction with the Fe(III)TPPCl-m-chloroperbenzoic acid (MCPBA) system at -30 deg C in the presence of γ-collidine, β-selective epoxidation of 3 proceeded predominantly while 1 was epoxidized stereoselectively.The stereoselectivities of these epoxidations closely resemble those with the Fe(III)TPPCl-iodosylbenzene system, which is known to give the ferryl ion.These results suggest that the O-O bond in the Fe(III)TPPCl-MCPBA complex cleaves mainly in the heterolytic manner (ferryl ion mechanism).Keywords---epoxidation stereoselectivity; cholesteryl acetate; cis-stilbene;
PHOTOINDUCED REACTIONS OF 3β-ACETOXYCHOLESTA-5,7-DIENE, 3β-ACETOXYCHOLEST-5-ENE, TETRAPHENYLCYCLOPENTADIENE AND 1,1-DIPHENYLETHYLENE WITH OXYGEN IN THE PRESENCE OF PHENYLSELENYL BROMIDE
Haynes, Richard K.,Hilliker, Audrey E.
, p. 509 - 512 (2007/10/02)
Whereas PhSeBr under irradiation with O2 in CH2Cl2 at -78 deg C acts as a photoxygenation catalyst to convert 3β-acetoxycholesta-5,7-diene and tetraphenylcyclopentadiene into the corresponding endoperoxides, and 3β-acetoxycholest-5-ene into 3β-acetoxycholest-5-en-7-one and the corresponding alcohols, it reacts with 1,1-diphenylethylene to give mainly a bromohydrin; bromine radicals arising by photodissociation of the PhSeBr are implicated as the active intermediates.
On the Mode of Oxygenation with the Ferric Perchlorate-Hydrogen Peroxide System
Muto, Toshiki,Urano, Chizuko,Hayashi, Toru,Miura, Toshiaki,Kimura, Michiya
, p. 1166 - 1171 (2007/10/02)
The reactions of three kinds of substrates with hydrogen peroxide catalyzed by ferric perchlorate in acetonitrile were investigated and compared with those occurring in the Fe(acac)3/alkylhydroperoxide system, which are governed by a radical process.Allylic oxidation and epoxidation both proceeded in the reaction of cholesteryl acetate, and the α-stereoselectivity of the epoxidation was enhanced by the presence of a radical scavenger.In the reactions of cis- and trans-stilbenes, stereospecific epoxidation by a non-radical process occurred, as well as a non-stereospecific reaction.The third substrate, adamantane, was shown to undergo more extensive oxygenation at its secondary carbon atoms than it did in the autooxidation and the Fe(acac)3/ROOH systems.Thus, it was concluded that the reaction in the Fe(ClO4)3/H2O2/CH3CN system involves both radical and non-radical processes. Keywords---ferric perchlorate; hydrogen peroxide; cholesteryl acetate; stilbene; adamantane; α-epoxidation of cholesteryl acetate; stereospecific epoxidation of stilbene; oxygenation of adamantane; non radical process; radical process
Iron-catalyzed Autoxidation of Cholesterol in the Presence of Unsaturated Long-Chain Fatty Acid
Muto, Toshiki,Tanaka, Jun,Miura, Toshiaki,Kimura, Michiya
, p. 3172 - 3177 (2007/10/02)
Oxy-functionalization of cholesteryl acetate (1a) occured, giving 3β-acetoxy-5,6-epoxycholestane (2a), 3β-acetoxycholest-5-en-7-one (3a), 3β-acetoxycholest-5-en-7-ol (4a), and an unidentified product (5), when 1a was oxidized by a system consisting of Fe(acac)3, and the hydroperoxide of an unsaturated long-chain fatty aicd (LH) such as oleic, linolic or linolenic acid (Table I).The epoxidation of stilbene by the same system was found to be non-stereospecific.These results and the fact that the reaction in this system was inhibited by a radical scavanger (BHT) were fairly compatible with those obtained with the Fe(acac)3-tBuOOH system, which is assumed to generate oxy and peroxy radicals.Autoxidation of 1a and cholesterol (1b) in the presence of Fe(acac)3 and LH proceeded after a time-lag of several hours and was also inhibited be BHT.The marked stereoselectivity of β-epoxidation (β/α+β=0.72) and the extent (about 30-40percent) of allylic oxidation in the autoxidation were in fair agreement with those found for 1a in the Fe(acac)3-LOOH system (Table II).Autoxidation of stilbene in the presence of Fe(acac)3 and LH also led to non-stereospecific epoxidation.Thus, the autoxidation of cholesterols (1a and 1b) in the Fe(acac)3-LH system was assumed to be a radical reaction in which LOO. and LO. are the attacking species.Keywords - autoxidation; cholesterol; co-oxidation; epoxidation; hydroperoxide; lipid peroxidation; radical pathway; stilbene; tris(acetylaceto)iron(III); unsaturated long-chain fatty acid
