Various carbon-carbon double bonds in olefins and α,β-unsaturatedketones were effectively reduced to the corresponding alkanes and saturated ketones, using ammoniumformate as a hydrogentransfer agent in the presence ofPd/C as catalyst in refluxing methanol.
以甲酸铵为氢转移剂,Pd/C为催化剂,甲醇回流。
Reactions of N-, S- and O-Nucleophiles with 3,4,6-Tri-O-benzyl-D-glucal Mediated by Triphenylphosphane Hydrobromide versus Those with HY Zeolite
作者:Amélia P. Rauter、Tânia Almeida、Ana I. Vicente、Verónica Ribeiro、João C. Bordado、João P. Marques、Fernando Ramôa Ribeiro、Maria J. Ferreira、Conceição Oliveira、Michel Guisnet
Circulardichroism (CD) spectra of the 2,2'-binaphthyl ester derived from Δ(5)-sterols showed not bisignate CD but diagnostic CD bands at around 210 and 240 nm. These bands might be attributable to an interaction between an olefinic chromophore and a binaphthyl one. Various types of unsaturated sterols were thus derivatized followed by complete hydrogenation, to give saturated sterols. As a result
源自 Δ(5)-甾醇的 2,2'-联萘酯的圆二色性 (CD) 光谱显示不是双信号 CD,而是在 210 和 240 nm 附近的诊断 CD 带。这些带可能归因于烯烃发色团和联萘发色团之间的相互作用。各种类型的不饱和甾醇被衍生化,然后完全氢化,得到饱和甾醇。结果,饱和甾醇的联萘衍生物的 CD 光谱显示出以 240 nm 为中心的双信号曲线(3S(β):正手性;3R(α):负手性)。这提出了一种基于诱导 CD 区分甾醇 C-3 位置的绝对立体中心的简单实用的方法。这一发现将对各种甾醇代谢物的分析做出重大贡献。
Flux analysis of cholesterol biosynthesis in vivo reveals multiple tissue and cell-type specific pathways
作者:Matthew A Mitsche、Jeffrey G McDonald、Helen H Hobbs、Jonathan C Cohen
DOI:10.7554/elife.07999
日期:——
to trace sterol flux through the two pathways in mice. Surprisingly, no tissue used the canonical K–R pathway. Rather, a hybrid pathway was identified that we call the modified K–R (MK–R) pathway. Proportional flux through the Bloch pathway varied from 8% in preputialgland to 97% in testes, and the tissue-specificity observed in vivo was retained in cultured cells. The distribution of sterol isotopomers
The metabolic sequence by which some 4,4-dimethyl sterols are converted into cholesterol
作者:Geoffrey F. Gibbons
DOI:10.1042/bj1440059
日期:1974.10.1
Cholest-8(14)-enol is the major radioactive component of the 4-di-demethyl sterol fraction biosynthesized from 4,4-dimethyl[2-(3)H(2)]cholest-8(14)-enol by ratliver microsomal fractions, and therefore the first steps in the biosynthesis of cholesterol from the latter compound probably involve removal of the 4-methyl groups. 4,4-Dimethylcholesta-8,14-dienol therefore is not an intermediate in this process