360-68-9Relevant articles and documents
Method for synthesizing cholesterol by taking BA as raw material
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, (2021/08/14)
The invention discloses a method for synthesizing cholesterol by taking BA as a raw material. A plant source raw material 21-hydroxy-20-methylpregna-4-en-3-one, also known as Shuangjiangchun or BA is taken as a raw material, and the cholesterol is synthesized by the steps of oxidation, Wittig reaction, acetylation, reduction, selective hydrogenation reduction and the like. The raw materials for synthesizing cholesterol are plant sources, the price is low, the safety is high, the risk of pathogenic bacteria and virus infection is avoided, and the synthesis method is easy to operate, high in yield, few in side reaction, environmentally friendly, good in economical efficiency and convenient for industrial production; and the invention solves the safety problem of the existing cholesterol product and the problems of high cost, environmental unfriendliness and unsuitability for large-scale industrial production in the synthesis technology.
Radical chain reduction of alkylboron compounds with catechols
Villa, Giorgio,Povie, Guillaume,Renaud, Philippe
supporting information; experimental part, p. 5913 - 5920 (2011/06/16)
The conversion of alkylboranes to the corresponding alkanes is classically per-formed via protonolysis of alkylboranes. This simple reaction requires the use of severe reaction conditions, that is, treatment with a carboxylic acid at high temperature (>150 °C). We report here a mild radical procedure for the transformation of organoboranes to alkanes. 4-tert-Butylcatechol, a well-established radical inhibitor and antioxidant, is acting as a source of hydrogen atoms. An efficient chain reaction is observed due to the exceptional reactivity of phenoxyl radicals toward alkylboranes. The reaction has been applied to a wide range of organoboron derivatives such as B- alkylcatecholboranes, trialkylboranes, pinacolboronates, and alkylboronic acids. Furthermore, the so far elusive rate constants for the hydrogen transfer between secondary alkyl radical and catechol derivatives have been experimentally determined. Interestingly, they are less than 1 order of magnitude slower than that of tin hydride at 80 °C, making catechols particularly attractive for a wide range of transformations involving C-C bond formation.
Cleavage of a p-cyanobenzyl group from protected alcohols, amines, and thiols using triethylgermyl sodium
Yokohama, Yasuo,Takizawa, Shuichi,Nanjo, Masato,Mochida, Kunio
, p. 1032 - 1033 (2007/10/03)
Alcohols, amines, and thiols protected with a p-cyanobenzyl group can be easily and quantitatively deprotected using triethylgermyl sodium under mild conditions.
Phosphine effects in the copper(I) hydride-catalyzed hydrogenation of ketones and regioselective 1,2-reduction of α,β-unsaturated ketones and aldehydes. Hydrogenation of decalin and steroidal ketones and enones
Chen, Jian-Xin,Daeuble, John F.,Stryker, Jeffrey M.
, p. 2789 - 2798 (2007/10/03)
The stereoselectivity and regioselectivity of the catalytic hydrogenation of ketones and α,β-unsaturated ketones and aldehydes using soluble copper(I) hydride catalysts have been investigated as a function of the ancillary phosphine ligand. While a relatively narrow range of aryldialkylphosphine ligands produce active hydrogenation catalysts, some ligands provide higher selectivity for 1,2-reduction of acyclic unsaturated carbonyl substrates than observed using the previously reported dimethylphenylphosphine-stabilized catalyst. The synthetic utility of this class of hydridic hydrogenation catalysts is illustrated by the hydrogenation of decalin and steroidal ketones and enones, the latter giving allylic alcohols with high selectivity. (C) 2000 Elsevier Science Ltd.
The reaction of alkyl peroxy radicals
Goosen, Andre,Kindermans, Sybrandus
, p. 1 - 8 (2007/10/03)
Secondary alkyl peroxy radicals generated from 4-phenyl-2-butyl-, 2-nonyl- and 3α-cholestanyl hydroperoxides at 45°C undergo Russell termination reactions in preference to non-terminating decomposition reactions. Non-terminating decomposition of 2-nonyl peroxy radicals afforded 2,5-nonanedione and 2,5-nonanediol due to intramolecular hydrogen abstraction reactions of alkoxy radicals. The radicals derived from 2-methyl-4-phenyl-2-butyl-, 2-methyl-5-phenyl-2-pentyl- and 2-methyl-6-phenyl-2-hexyl hydroperoxides afforded benzylic functionalized products due to intermolecular reactions. 2-Hexylperoxy radicals generated in excess alcohols ineffectively abstracted the α-hydrogens of alcohols. These results demonstrate the low reactivity of alkyl peroxy radicals.
Mechanism of cholesterol reduction to coprostanol by Eubacterium corpostanoligenes ASTCC 51222
Ren, Dewei,Li, Ling,Schwabacher, Alan W.,Youbg, Jerry W.,Beitz, Donald C.
, p. 33 - 40 (2007/10/03)
The mechanism of reduction of cholesterol to coprostanol by Eubacterium coprostanoligenes ATCC 51222 was studied by incubating the bacterium with a mixture of α- and β-isomers of cholesterol.Coprostanol, isolated after incubation of cholesterol in a growth medium under anaerobic conditions, retained 97percent of the tritium originally presented in cholesterol.The majority of this tritium (64percent), however, was in the C-6 position in coprostanol, which showed that the conversion of cholesterol into coprostanol by E. coprostanoligenes involved the intermediate formation of 4-cholesten-3-one followed by the reduction of the latter to coprostanol.In resting cell assays in which washed bacterial cells were incubated with micellar cholesterol in phosphate buffer at 37 deg C, both 4-cholesten-3-one and coprostanone were produced in addition to coprostanol.Furthermore, 5-cholesten-3-one, 4-cholesten-3-one, and coprostanone were converted efficiently to coprostanol by E. coprostanoligenes.These results support the hypothesis that the major pathway for reduction of cholesterol by E. coprostanoligenes involves the intermediate formation of 4-cholesten-3-one followed by reduction of the latter to coprostanol through coprostanone as an intermediate. (Steroids 61:33-40, 1996) - Key words: dual-labeled cholesterol, coprostanol; cholesterol reduction; Eubacterium; NMR.
Formation of ketones from alkyl nitrites in the solid state
Kinbara, Kazushi,Takezaki, Hiroshi,Kai, Akiyoshi,Saigo, Kazuhiko
, p. 217 - 218 (2007/10/03)
Alkyl nitrites selectively afforded the corresponding ketones upon photoirradiation in the solid state. It was suggested by the X-ray crystallographic analysis that the cavity in crystal and the initial conformation of the nitroso group had an influence on the yield of the ketones.
Efficient method for inversion of secondary alcohols by reaction of chloromethanesulfonates with cesium acetate
Shimizu, Takeshi,Hiranuma, Sayoko,Nakata, Tadashi
, p. 6145 - 6148 (2007/10/03)
Inversion of a variety of secondary alcohols using the (chloromethylsulfonyl)oxy group as a favorable leaving group with cesium acetate in the presence of 18-crown-6 has been performed to give the inverted acetates in high yields.
Electrochemical preparation and some reactions of alkoxy triphenylphosphonium ions
Maeda,Koide,Maki,Ohmori
, p. 1076 - 1080 (2007/10/02)
The formation of an alkoxy triphenylphosphonium ion by anodic oxidation of Ph3P in the presence of an alcohol was investigated. When a CH2Cl2 solution of Ph3P, Ph3P-H·ClO4-, and an alcohol was subjected to constant-current electrolysis in an undivided cell equipped with a graphite anode and a Pt cathode, the 31P-NMR spectra of the resulting electrolyte showed that alkoxy triphenylphosphonium perchlorates (2) were formed in good to fair yields from primary and secondary aliphatic alcohols, while allylic and bencyclic alcohols were transformed to the corresponding alkyl phosphonium ions, and in the case of tertiary aliphatic alcohols, no formation of the corresponding alkoxy or alkyl phosphonium ions was recognized at all. The isolation of 2 thus formed was achieved in good yields by a simple procedure. For the electrolysis, Ph3P+H·BF4- could be utilized instead of the perchlorate salt, giving an alkoxy triphenylphosphonium tetrafluoroborate (3) from primary and secondary aliphatic alcohols. The reaction of the alkoxy phosphonium ion prepared from β- and α-cholestanol with various nucleophiles such as Bu4N+·X- (X = Br, Cl, F, N3, SCN), PhSH, and PhOH was examined. The results indicated that the reaction site of the phosphonium ions is dictated by the identity of the nucleophile. A soft nucleophile was apt to attack at the α-carbon, giving the corresponding SN2 reaction product in a good yield, while a hard one tended to react at the phosphorus of the phosphonium ion, leading to the regeneration of the cholestanol.
