17608-41-2Relevant academic research and scientific papers
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.
Chemical Bypass of General Base Catalysis in Hedgehog Protein Cholesterolysis Using a Hyper-Nucleophilic Substrate
Ciulla, Daniel A.,Jorgensen, Michael T.,Giner, José-Luis,Callahan, Brian P.
supporting information, p. 916 - 918 (2018/02/07)
Proteins in the hedgehog family undergo self-catalyzed endoproteolysis involving nucleophilic attack by a molecule of cholesterol. Recently, a conserved aspartate residue (D303, or D46) of hedgehog was identified as the general base that activates cholesterol during this unusual autoprocessing event; mutation of the catalyzing functional group (D303A) reduces activity by >104-fold. Here we report near total rescue of this ostensibly dead general base mutant by a synthetic substrate, 3β-hydroperoxycholestane (3HPC) in which the sterol-OH group is replaced by the hyper nucleophilic-OOH group. Other hedgehog point mutants at D303, also unreactive with cholesterol, accepted 3HPC as a substrate with the rank order: WT > D303A ～D303N D303R, D303E. We attribute the revived activity with 3-HPC to the α-effect, where tandem electronegative atoms exhibit exceptionally high nucleophilicity despite relatively low basicity.
Powerful Continuous-Flow Hydrogenation by using Poly(dimethyl)silane-Supported Palladium Catalysts
Kobayashi, Shu,Okumura, Mikiko,Akatsuka, Yuichi,Miyamura, Hiroyuki,Ueno, Masaharu,Oyamada, Hidekazu
, p. 4025 - 4029 (2015/12/26)
We developed poly(dimethyl)silane-supported Pd catalysts that are readily prepared from Pd(OAc)2, poly(dimethyl)silane, and Al2O3. The immobilization was achieved for the first time with a support that does not contain benzene rings. The Pd catalyst thus prepared was found to have higher hydrogenation activity than Pd/C. Furthermore, the catalyst was used in continuous-flow hydrogenation with various substrates, including simple liquid substrates (neat) and dissolved solid substrates. Vegetable oils, squalenes, and phosphatidylcholine were successfully hydrogenated on gram to kilogram scales.
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.
Action of lithium ethylenediamine on 1,4-diketone
Ghosh, Pranab,Chakraborty, Prasanta
experimental part, p. 1125 - 1128 (2011/06/19)
Reactions of lithium ethylenediamine (Li/EDA) have been carried out on 1,4-diketones such as cholest-4(5)-en-3,6-dione (1) and hexane-2,5-dione (7). The resulting compounds have been characterized by optical rotation, IR, mass spectra and by comparison with authentic samples.
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.
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.
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.
