- Oxidation of cholesterol by a biomimetic oxidant, cetyltrimethylammonium dichromate
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The oxidation of cholesterol by cetyltrimethylammonium dichromate (CTADC) in dichloromethane (DCM) yielded 7-dehydrocholesterol, while with addition of acetic acid in DCM the product was found to be 5-cholesten-3-one. The kinetics of oxidation of cholesterol by CTADC in DCM, in the presence of acid, was investigated with change in [acid], [cholesterol], [CTADC], [surfactant], temperature, and solvents. The reaction was found to be first order with acetic acid and fractional order with CTADC and cholesterol. Michaelis-Menten-type kinetics was observed with respect to cholesterol. The solvent isotope effect was found to be k(D2O)/k(H2O) = 0.72. The observed experimental data suggest that the reaction occurs in reversed micellar system, akin to an enzymatic environment, and the reaction path involves the intermediate formation of an ester complex, which undergoes decomposition to give the product.
- Patel, Sabita,Mishra
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- Novel industrial method for preparing vitamin D3 by taking stigmasterol as raw material
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The invention provides a novel industrial method for preparing vitamin D3 by taking stigmasterol as a raw material. The method comprises the following steps: sequentially carrying out hydroxyl acetylation, side chain oxidation, side chain isopentane reduction and hydrogenation on stigmasterol to obtain cholesterol acetate, and then sequentially carrying out oxidation, hydrazone formation, hydrazone removal, hydrolysis, illumination and the like to obtain the vitamin D3. The invention provides a novel method for preparing vitamin D3 from stigmasterol, and the method has the advantages of mild reaction conditions and high yield, and is suitable for industrial production.
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- PREPARATION OF 7-DEHYDROCHOLESTEROL USING SPECIFIC AROMATIC SOLVENTS
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The present invention relates to a new synthesis of 7- dehydrocholesterol or itsOH-protected forms of the formula I by the reaction of a compound of formula (ll)in the presence of a solvent of formula (III), comprising the step (a) wherein a salt of the formula (II) is added to a solvent of the formula (III) at a temperature of between 60 °C and the boiling point of said solvent. This process leads to a significant reduction in the level of the by-product of formula (V).
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- Preparation method of 7-dehydrocholesterol for production of vitamin D3
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The invention particularly discloses a preparation method of 7-dehydrocholesterol for production of vitamin D3. The preparation method comprises the following steps: an esterification reaction, a bromination reaction, a debromination reaction and a saponification hydrolysis reaction. The esterification reaction comprises the following steps: adding cholesterol, an acid-binding agent and a solid catalyst into petroleum ether, carrying out heating to 45-50 DEG C in a nitrogen atmosphere, dropwise adding benzoyl chloride, performing heating to 78-82 DEG C after dropwise adding, conducting stirring for a reaction for 3-5 hours, adding distilled water to quench the reaction, performing filtering to obtain filter residues and a filtrate, extracting the filter residues with distilled water, concentrating an oil layer, then adding acetone, carrying out a reflux reaction for 30-40 minutes, conducting cooling to 20-30 DEG C, and performing filtering to obtain cholesterol benzoate; and soaking, filtering and drying the filter residues to obtain a solid desiccant, and repeatedly using the solid desiccant. The method has the advantage of facilitating cyclic utilization of the catalyst.
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- ORGANIC SOLVENT NANOFILTRATION OF 7-DEHYDROCHOLESTEROL OR 25-HYDROXY-7-DEHYDROCHOLESTEROL OR THEIR OH PROTECTED FORMS
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The present invention relates to the purification of 7-dehydrocholesterol or 25-hydroxy-7-dehydrocholesterol or their OH-protected forms, respectively. It has been found that the process using organic solvent nanofiltration allows an efficient reduction of the amount of a new higher molecular compound which is formed in a 5 new synthesis process of of 7-dehydrocholesterol or 25-hydroxy-7-dehydrocholes- terol or their OH-protected forms in small amounts. Said new higher molecular compound can be used as colorant.
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- Methods for preparing cholesterol, and derivatives and analogs thereof
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The present invention relates to the field of pharmaceutical chemistry, and in particular to methods of preparing cholesterol,and derivatives and analogs thereof. The cholesterol derivatives include, but not limited to, 7-dehydrocholesterol, 25-hydroxycholesterol, 25- hydroxy7dehydrocholesterol and ergosterol. In the invention, phytosterol can be used as a raw material to prepare the compound shown in the formula I through microbial conversion, and then cholesterol and the derivatives and analogues thereof are prepared.
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- IMPROVED, COST EFFECTIVE PROCESS FOR SYNTHESIS OF VITAMIN D3 AND ITS ANALOGUE CALCIFEDIOL FROM ERGOSTEROL
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Disclosed herein is an improved and efficient process for synthesis of vitamin D3 and its analogue Calcifediol from Ergosterol. Particularly, the present invention discloses the synthesis of key intermediate 3β-tert-Butyldimethylsilyloxy-22-hydroxy-23,24-bisnorchola-5,7-diene (5), and novel intermediate β-tert-Butyldimethylsilyloxy-22-iodo-23,24-bisnorchola-5,7-diene (9) by a simple and cost effective process. The industrially viable processes for preparation of said intermediate(s) results in providing provitamins with various side chains and the desired products in high yield.
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Page/Page column 23; 43
(2021/01/29)
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- New industrial method for producing vitamin D3 by taking wool fat as raw material
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The invention provides a new industrial method for producing vitamin D3 by taking wool fat as a raw material. The new industrial method comprises the following steps: carrying out saponification and primary purification on the wool fat in a low alcohol solution, thus obtaining a cholesterol crude product; directly carrying out acetylation on the cholesterol crude product, thus obtaining high-purity cholesterol acetate; then sequentially carrying out oxidizing, hydrazone forming, hydrazone removing, hydrolyzing, illuminating and the like, thus obtaining the vitamin D3. A production technology disclosed by the invention is efficient, green and environment-friendly, is high in product yield and is suitable for industrial production, and the manufacturing cost of the vitamin D3 is greatly reduced; a saponification technology is ingenious in filtrate treatment, has no generation of waste liquid and waste and is more beneficial for environment protection.
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- Synthesis and biological activity evaluation of novel peroxo-bridged derivatives as potential anti-hepatitis B virus agents
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Previous studies have demonstrated that natural steroid compounds containing a peroxide bridge exhibited potential anti-hepatitis B virus activity. To continue our research, a simple and regioselective methodology, using Eosin Y as a clean photosensitized oxidation catalyst, was developed for the synthesis of a peroxide bridge in steroids. The method that using Eosin Y as the catalyst was exposed to visible light and furbished in high yields, did not involve tedious work-up or purification, and avoided using environmentally hazardous solvents. It can be regarded as a green protocol. Moreover, a series of cholesterol and β-sitosterol derivatives containing a peroxide bridge were synthesized using this method and screened for their anti-HBV activity. Among the compounds synthesized in this research, 5α,8α-cyclicobioxygen-6-vinyl-3-oxo-cholesterone (1f, 3.13 μg ml?1) had the most potent activity with inhibition rates of 77.45% ± 6.01% and 58.73% ± 8.64% on the secretion of HBsAg and HBeAg antigens, respectively, after 8 days. Further acute toxicity test showed that the LD50 value of compound 1f was 362.46 mg kg?1 after an intraperitoneal injection in mice. Moreover, structure-activity relationships of cholesterol and β-sitosterol derivatives were briefly discussed.
- Jia, Menglu,Zhao, Rui,Xu, Bing,Yan, Wenqiang,Chu, Fuhao,Gu, Hongshun,Xie, Tianxin,Xiang, Hongjun,Ren, Jian,Chen, Dagang,Wang, Penglong,Lei, Haimin
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p. 148 - 151
(2017/02/05)
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- PROCESS FOR PREPARATION OF 7-DEHYDROCHOLESTEROL
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The invention discloses an improved cost-effective process for preparation of 7-Dehydrocholesterol of formula I with good yield and purity, comprising:a) epimerizing 7(alpha+beta) bromo protected cholesterol in presence of tetrabutyl ammonium bromide in toluene or a ketonic solvent or combinations thereof to obtain predominantly 7.alpha-bromo 3-protected cholesterol; b) Reacting 7.apha-bromo 3- protected cholesterol with substituted or unsubstituted thiophenol or its salts in presence of a liquor ammonia to obtain predominantly 7β-thiophenyl)-3-protected cholesterol; c) Oxidizing 7. beta. - thiophenyl 3-protected cholesterol in presence of Cumene hydrogen peroxide and Titanium tetraisopropoxide to obtain 7. beta. -phenyl sulfoxide 3-protected cholesterol; d) Converting 7. beta. -phenyl sulfoxide 3-protected cholesterol into 7-Dehydro 3-protected cholesterol in presence of base; e) purifying 7-Dehydro 3-protected cholesterol by suspending in a suitable organic solvent; and f) Deprotecting the 7-Dehydro 3-protected cholesterol by treating with alkali in presence of methanol to obtain 7-Dehydrocholesterol followed by purification of 7-Dehydrocholesterol from an organic solvent.
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Page/Page column 14
(2015/11/27)
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- Reactivities and products of free radical oxidation of cholestadienols
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7-Dehydrocholesterol (7-DHC) is the most oxidizable lipid molecule reported to date, with a propagation rate constant for free radical peroxidation that is 200 times that of cholesterol. To better understand the high reactivity of 7-DHC and elucidate the reaction mechanism, we synthesized conjugated and skipped nonconjugated cholestadienols that would give one of the two putative pentadienyl-radical intermediates formed in 7-DHC peroxidation. The additional dienols include 6,8(9)-dienol, 5,8(14)-dienol, 6,8(14)-dienol, and the biologically important 8-dehydrocholesterol (8-DHC; 5,8(9)-dienol). We found that all of the dienols are significantly (at least 40 times) more reactive than cholesterol. Among them, dienols leading to the formation of the pentadienyl radical in ring B (termed endo-B) of the sterol are more reactive than those leading to the pentadienyl radical spanning rings B and C (termed exo-B). By comparing the oxysterol profile formed from 7-DHC and those formed from 8-DHC and 5,8(14)-dienol, products formed from abstraction of the hydrogen atoms at C-9 and C-14 (H-9 or H-14 mechanism) were clearly differentiated. When the oxidation was carried out in the presence of the good hydrogen atom donor α-tocopherol, the oxysterol profile of 7-DHC peroxidation differed distinctly from the profile observed in the absence of the antioxidant and resembles more closely the profile observed in biological systems. This study suggests that oxidative stress and the accumulation of oxysterols should be considered as two key factors in cholesterol biosynthesis or metabolism disorders, where dienyl sterol intermediates are accumulated.
- Xu, Libin,Porter, Ned A.
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supporting information
p. 5443 - 5450
(2014/05/06)
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- Synthesis of 7-dehydrocholesterol through hexacarbonyl molybdenum catalyzed elimination reaction
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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.
- Ur Rahman, Faiz,Tan, Tian Wei
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p. 247 - 254
(2012/05/05)
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- A convenient method for the preparation of Δ4,7-steroidal 3-ketones and Δ5,7 sterols
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A method is described for the preparation of Δ4,7-steroidal ketones or Δ5,7-sterols from Δ5-sterols via the sequence Wettstein-Oppenauer oxidation, trifluoroacetylation to give the Δ2,4,6-enol ester, and acid catalyzed isomerization to the Δ3,5,7-enol ester, followed by acid hydrolysis, or sodium borohydride reduction, respectively.
- Giner, Jose-Luis,Zhao, Hui
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p. 605 - 609
(2007/10/03)
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- Novel Photosensitizers for the E/Z-Isomerization of Trienes. Part 1. Synthesis and Application
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Uranine and its thioxanthene and selenoxanthene analogues, as well as the disodium salts of o-(6-hydroxy-3-oxo-3H-xanthen-9-yl)benzenesulphonic acid and its thioxanthene and selenoxanthene analogues, show different photosensitizer properties in the E/Z-isomerization of trienes.This has been verified by applying them to the technically useful conversion of tachysterol into previtamin D.The synthesis of the novel photosensitizers with thioxanthene and selenoxanthene moieties are also described.
- Pfoertner, Karl-Heinz
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p. 523 - 526
(2007/10/02)
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- SYNTHESIS OF HIGH SPECIFIC ACTIVITY -7-DEHYDROCHOLESTEROL. CONVERSION TO ECDYSONE IN FOLLICLE CELLS OF LOCUSTA (INSECTS)
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In previous studies we have characterized the last steps of the biosynthetic pathway of the insect moulting hormone ecdysone.We are now extending our studies to the early steps and have postulated that 7-dehydrocholesterol is one of the earliest precursor molecules.To probe this hypothesis we have synthesized this molecule under tritiated form with high specific activity (2 TBq/mmol).We have devised an original pathway which includes, as a last step, the tritiation at positions 1α and 2α.In a first series of investigations, we have demonstrated that injected 7-dehydrocholesterol was efficiently converted in vivo by the ovaries of adult females of Locusta migratoria into conjugated ecdysone and 2-deoxyecdysone.In vitro incubations of 7-dehydrocholesterol with a 1.000g supernatant of a follicle cell homogenate have occasionaly yielded conversion rates into ecdysone which were as high as 10percent.
- Dolle, Frederic,Kappler, Christine,Hetru, Charles,Rousseau, Bernard,Coppo, Michele,et al.
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p. 5305 - 5316
(2007/10/02)
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- Triene Photophysics and Photochemistry: Previtamin D3
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The origin of the wavelenght dependent photochemical behavior of previtamin D3 was investigated.The fluorescence spectrum and quantum yield of previtamin D3 were determined at 302 and 307 nm, and both the intensity distribution and the fluorescence quantum yields were found to be independent of excitation energy.A large Stokes shift was observed which is consistent with an excited state torsional relaxation about the central double bond of the triene.The excited state displacement was reproduced by QCFF/PI calculations of the ground and excited states of a model compound.The excited state involved in the absorption and emission spectra is discussed.
- Dauben, William G.,Share, Paul E.,Ollmann, Richard R., Jr.
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p. 2548 - 2554
(2007/10/02)
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- A Convenient Synthesis of Cholesta-1,5,7-trien-3β-ol
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Cholesta-4,6-dien-3β-ol (4) was obtained selectively by the dehydrobromination of 7-bromocholesterol with a base in the presence of a catalytic amount of tetrabutylammonium bromide.The oxidation of 4 with 2,3-dichloro-5,6-dicyano-p-benzoquinone gave cholesta-1,4,6-trien-3-one (7).Treatment of 7 with isopropenyl acetate under acidic conditions afforded (3-acetoxy-1,3,5,7-cholestatetraene which was reduced with calcium borohydride to yield cholesta-1,5,7-triene-3β-ol (2).
- Tachibana, Yoji
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p. 3702 - 3704
(2007/10/02)
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- Bridged-ring steroids. III. The synthesis of bridged steroids with a bicycloheptane ring B system
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Reaction of cholesta-5,7-dien-3β-yl 2-tetrahydropyranyl ether with bromoform and potassium tert-butoxide gave 3',3'-dibromo-3',6β-dihydrocyclopropa-5a-cholest-7-en-3β-yl 2-tetrahydropyranyl ether (1c), which on treatment with lithium aluminium hydride and water gave 5,8α-methano-5α-cholest-6-en-3β-yl 2-tetrahydropyranyl ether (2c).This has been converted to 3β-acetoxy-5,8α-methano-5α-cholestan-6-one (16c) and 3β-acetoxy-5,8α-methano-5α-cholestan-7-one (17c).A preliminary investigation of the photochemistry of 16c and 17c has shown that the incorporation of the bicycloheptan-2-one system in the B ring of a steroid results in photoreactions of this system that are different from those observed in the case of simple bicycloheptan-2-ones.
- Yates, Peter,Winnik, Francoise M.
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p. 2501 - 2506
(2007/10/02)
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