Reductive Coupling of Carbonyl Compounds to Pinacols with Zinc in THF-Saturated Aqueous Ammonium Chloride

Summary.  In the presence of metallic zinc, aldehydes and ketones experience reductive coupling in tetrahydrofuran-saturated aqueous ammonium chloride (5:3) to afford the corresponding pinacols in moderate to high yields. Received October 23, 2000. Accepted (revised) December 12, 2000     

Microwave Promoted Reductive Coupling of Carbonyl Compounds to Bis(Trimethylsilyl) Pinacols Under Solvent-Free Conditions

Reductive coupling of carbonyl compounds was performed with trimethylchlorosilane (TMS-Cl) on montmorillonite K10 clay in conventional microwave oven in short time wih quantitative yields of bis(trimethylsilyl) pinacols.     

Reductive Cleavage of Azo Compounds by Zinc and Ammonium Chloride

Abstract

Azo compounds are reduced to corresponding anilines with zinc dust in the presence of ammonium chloride in methanol at room temperature.     

Reductive Dehalogenation of Arylhalides and Alkylhalides with Zinc in THF Saturated Aqueous Ammonium Chloride

A low‐cost and highly effective zinc/THF‐saturated aqueous ammonium chloride has been developed for dehalogenation of arylhalides and alkylhalides in aqueous systems.     

金属锌促进羰基化合物水相嚬呐偶合反应

报道了一种简便、有效的水相噤呐偶合反应。在含有少量季铵盐或季磷盐的氯化铵水溶液中．用金属锌促进羰基化合物进行水相噘呐偶合反应，其中加入的少量季铵盐或季磷盐有助于显著提高反应产率，噘呐醇产率由53％提高到87％。但噘呐偶合反应的产率受羰基周围环境的立体位阻影响较大，在此条件下，金属锌可有效地促进芳香族醛化合物进行水相噘呐偶合反应，得到产率较高的噘呐醇，但非对映异构体选择性差，而脂肪族醛化合物得到的噘呐醇产率较低，在同样条件下，酮类化合物不能顺利进行噘呐偶合反应。     

金属锌促进羰基化合物水相嚬呐偶合反应

报道了一种简便、有效的水相嚬呐偶合反应。在含有少量季铵盐或季磷盐的氯化铵水溶液中,用金属锌促进羰基化合物进行水相嚬呐偶合反应,其中加入的少量季铵盐或季磷盐有助于显著提高反应产率,嚬呐醇产率由53%提高到87%。但嚬呐偶合反应的产率受羰基周围环境的立体位阻影响较大,在此条件下,金属锌可有效地促进芳香族醛化合物进行水相嚬呐偶合反应,得到产率较高的嚬呐醇,但非对映异构体选择性差,而脂肪族醛化合物得到的嚬呐醇产率较低,在同样条件下,酮类化合物不能顺利进行嚬呐偶合反应。     

羰基化合物还原偶联为频呐醇反应的研究新进展

综述了近几年来羰基化合物还原偶联为频呐醇反应的研究新进展．     

水相中锌促进的羰基化合物频哪醇偶联反应实验设计

介绍水相中锌促进的羰基化合物频哪醇偶联反应的实验设计。通过苯甲醛频哪醇偶联反应得到相应的1,2-二苯基．1,2-乙二醇,学习水相有机反应和微量反应的基本操作,加强基础研究、绿色化学与有机化学实验之间的紧密联系。     

Reductive Coupling Reaction of Carbonyl Compounds In a TiCl4/Ga Bimetal Redox System

For about 20 yeers the chemisty of low-valent titanium complexes has received great attention¹ and now many of the reactions involving them are commonly used in synethesis². The reactivity, of the low-valent titanium slurries, obtained after reduction of titanium trichloride or titanium tetrachloride by means of strong reducting agents such as magnesium, zinc in tetrahydrofuran has also been studied^3-4. In 1995,we reported that carbonyl compounds react with ethyl trichloracetate and iodoacetonitrile in a PbCl₂/Ga bimetal redox system⁵. Herein, we report reductive coupling reaction of carbonyl compound to afford E-alkenes with TiCl₄/Ga bimetal redox system. Simplicity of produre and moderate to excellent yields of product.     

Coupling Reaction of Carbonyl Compounds Mediated by Gallium Metal in Aqueous Media

A simple and effective pinacol coupling of various aromatic aldehydes mediated by gallium in good yields has been carried out. The reaction is highly effective in water in the prurience of KOH or HCl and was strongly affected by the steric environ-ment surrounding the carbonyl group. Aliphaflc aldehydes, ke-tones and aromatic ketones appear inert under the same reac-tion conditions.     

水溶液中锌电极诱发芳香醛的还原偶联反应

以锌片为电极芳香醛为底物在酸性条件下电合成呐醇,探讨了电流密度、反应时间、盐酸浓度对产率的影响.最佳反应条件如下:电流密度2.4A/dm2,反应时间60min,盐酸用量(5mL)2mol/L,呐醇的产率范围14%～80%.     

FeCl3催化羰基化合物与芳烃的还原Friedel-Crafts烷基化反应

在二甲基氯硅烷作用下, FeCl3能催化羰基化合物(醛、酮)与芳烃及噻酚的还原Friedel-Crafts烷基化反应, 在温和的条件下一步实现羰基化合物的还原和C—C键的构造.     

超声波作用下锌粉诱发芳香醛的还原偶联反应

超声波作用下,芳香醛在Zn-10％NaOH(aq．)-bleOH体系中反应,室温下25min～60min内得到41％～97％的偶联产物邻二醇。     

Low-Valent Titanium Induced Reductive Coupling of Nitriles with Nitro Compounds

The intermolecular and intramolecular reductive coupling of a cyano group with a nitro group induced by a low-valent titanium reagent prepared from TiCl₄/Sm was studied. Amidines and 2-aminoquinolines derivatives are preparied in good yields under mild conditions respectively.     

Exomethylene Cephams via Zinc/Ammonium Chloride Reduction of Acetoxymethyl Cephems

3-Exomethylene cephalosporins have been prepared in good yield by reduction of esters of cephalosporanic acids with activated zinc dust and ammonium chloride.     

水相中Pd/C催化的杂环芳卤的还原偶联反应研究

在H₂O-alcohol体系中通过Pd/C催化的还原偶联反应由杂环芳卤高收率的得到了二芳基化合物. 该方法操作简单, 环境友好, Pd/C可重复使用, 无需相转移催化剂也能得到较高收率. 讨论了醇、碱的种类和用量以及不同底物对反应收率的影响.     

Reduction of Carbonyl Compounds to Alcohols Using Ferric Chloride - Zinc-Dimethylformamide-Water System

Carbonyl Compounds have been reduced into the corresponding alcohols in moderate to good yields at room temperature using Ferric Chloride-Zinc-Dimethyl-Formamide-Water System.     

Reductive Deoxygenation of Carbonyl to Methylene

The reductive deoxygenation of aldehydes and ketones into the corresponding alkanes is accomplished by LiAlH4, in the presence of Lewis acid InBr3. It provides a convenient method to complete the transformation from carbonyl compounds to alkanes.     

Reductive Amination of Carbonyl Compounds with Ammonia and Hydrogenation of Nitriles to Primary Amines with Heterogeneous Cobalt Catalysts

Reductive amination of aldehydes/ketones with aqueous NH3 and hydrogenation of nitriles to primary amines with Co catalysts were reported. Co@NC-700 exhibited remarkable activity and high selectivity for the reductive amination of aldehydes/ketones with aqueous NH3 and the hydrogenation of nitriles to primary amines. Several primary amines can be obtained with good to excellent yields via the reductive amination of aldehydes/ketones and the hydrogenation of nitriles. The nitrogen-doped carbon(C)-supported Co@NC-700 metal catalyst was prepared via the pyrolysis of bioMOF Co/adenine in activated C. Co@NC-700 can be reused five times without evident loss of activity.