IBX in an ionic liquid: eco-friendly oxidation of 17α-methylandrostan-3β,17β-diol, an intermediate in the synthesis of anabolic oxandrolone
摘要:
An easily available hypervalent iodine(V) reagent, 2-iodoxybenzoic acid (IBX) immobilized in the ionic liquid [bmim][Br] was found to be an efficient and eco-friendly protocol for the oxidation of 17alpha-methylandrostan-3beta,17beta-diol (1). At ambient temperature oxidation of 1 with lBX gave mestanolone (2) in good yield and with an increased stoichiometric amount of IBX, oxidation adjacent to the carbonyl functionality (alpha,beta-unsaturation) occurred to give dehydrogenated 17 beta-hydroxy- 17alpha-methyl-Delta'-and rosten-3-one (3) as the major product in a one-pot reaction, The product is easily obtained by extraction with diethyl ether and evaporation of the solvent. (C) 2004 Elsevier Ltd. All rights reserved.
Selective activation of secondary C–H bonds by an iron catalyst: insights into possibilities created by the use of a carboxyl-containing bipyridine ligand
4′-dicarboxylic acid), which could activate the C–H bonds of cycloalkanes with high secondary (2°) C–Hbond selectivity. A turnover number (TN) of 11.8 and a 30% yield (based on the H2O2 oxidant) were achieved during the catalytic oxidation of cyclohexane by 1 under irradiation with visiblelight. For the transformation of cycloalkanes and bicyclic decalins with both 2° and tertiary (3°) C–H bonds, 1 always preferred
在这项工作中,我们报告发现了一种含羧基的铁催化剂1(Fe II -DCBPY,DCBPY = 2,2'-联吡啶-4,4'-二羧酸),该催化剂可以活化环烷烃的C–H键具有较高的次级(2°)CH键选择性。在H2O2的催化氧化过程中达到了11.8的周转数(TN)和30%的收率(基于H 2 O 2氧化剂)。环己烷在可见光照射下,按1。对于具有2°和叔(3°)C–H键的环烷烃和双环十氢化萘的转化,1总是优选将2°C–H键氧化为相应的酮和醇产物;在7个示例中,2°/ 3°的比率介于78/22和> 99/1之间。用18 O同位素标记实验,ESR实验,PPh 3方法和过氧化氢酶方法表征了氧化过程中的反应过程。1的成功表明,除了使用体积较大的催化剂外,使用体积较小的分子铁络合物作为催化剂也可以实现较高的2°C–H键选择性。
Efficient and Practical Arene Hydrogenation by Heterogeneous Catalysts under Mild Conditions
An efficient and practicalarenehydrogenation procedure based on the use of heterogeneous platinum group catalysts has been developed. Rh/C is the most effective catalyst for the hydrogenation of the aromatic ring, which can be conducted in iPrOH under neutral conditions and at ordinary to medium H2 pressures (<10 atm). A variety of arenes such as alkylbenzenes, benzoic acids, pyridines, furans, are
Catalytic hydrogenation of aromatic rings catalyzed by Pd/NiO
作者:Yanan Wang、Xinjiang Cui、Youquan Deng、Feng Shi
DOI:10.1039/c3ra45600e
日期:——
A simple and efficient heterogeneous palladium catalyst was prepared for aromaticringhydrogenation. The catalyst was prepared by a reduction-deposition method and exhibited high activity and selectivity for the hydrogenation of a variety of substituted aromatic compounds to the corresponding cyclohexane and cyclohexanol derivatives with up to 99% yields. The catalyst was characterized by BET, TEM
Synthese von (η5-cyclopentadienyl)dichloro-s-alkoxititan(IV)-komplexen. Eine bestandsaufnahme der reaktion von titanocendichlorid mit alkoholen
作者:Udo Höhlein、Rainer Schobert
DOI:10.1016/0022-328x(92)80005-i
日期:1992.2
The synthesis of (η5-cyclopentadienyl)dichloro-s-alkoxititan(IV) from the corresponding alcohols and titanocene dichloride proceeds under mild conditions by substitution of one Cp ligand in the presence of triethylamine. This procedure is also applicable to chiral 1,4-t, t-diols, thus avoiding the use of the rather expensive η5-cyclopentadienyltrichlorotitan(IV) as a starting material. The title compounds
Compounds that have agonist activity at one or more of the SlP receptors are provided. The compounds are sphingosine analogs that, after phosphorylation, can behave as agonists at S lP receptors.