18769-46-5Relevant 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.
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.
