Enantioselective Synthesis of Chiral 1-Ferrocenyl Alcohol via CBS-Reduction

In recent years present interest in the synthesis of chiral ligands has directed attention to the preparation of optically active compounds bearing a ferrocenyl or other organometallic group at the alpha carbon atom. The chirality of all the optically active ferrocenes is due to the ferrocene planar chirality. And many chiral phosphines or amines bearing a ferrocene unit have been used as ligands for transition metal catalyzed asymmetric transportations1. These complexes have been convenien…     

An Efficient Prins Cyclization for Stereoselective Synthesis of Tetrahydropyran from Imines and Homoallyl Alcohols

An unprecedented protocol has been developed for the efficient synthesis of substituted tetrahydropyrans via a bismuth‐promoted Prins cyclization of imines with homoallyl alcohols. In the presence of 40 mol% BiCl₃, a wide variety of imines react smoothly with homoallyl alcohols at room temperature to give the corresponding 4‐chlorotetrahydropyran derivatives in good to excellent yields.     

硫酸亚铈催化的芳香化合物与苄基醇、烯丙醇类化合物以及苄基氯的傅-克烷基化反应研究

硫酸亚铈作为一种便宜的和有效的催化剂催化芳香化合物与苄基醇、烯丙醇类化合物和苄基氯的傅-克烷基化反应. 在1～10 mol%的硫酸亚铈存在下, 芳香化合物分别与苄基醇、烯丙醇类化合物和苄基氯能够顺利有效地进行傅-克烷基化反应. 此外, 催化剂能回收, 再次使用三次也没有明显地失去催化活性.     

A mild and efficient method for the oxidation of benzylic alcohols by two-phase electrolysis

Electrochemical oxidation of benzylic and substituted benzylic alcohols by two-phase electrolysis yields the corresponding aldehydes as products. The reaction was carried out in a single compartment cell with platinum electrodes at room temperature in chloroform using an aqueous sodium bromide solution (25%) containing a catalytic amount of HBr. The two-phase electrolysis resulted in high yields (74-96%) of benzaldehyde from primary alcohols and secondary alcohols were oxidized to the corresponding ketone but only in low yields under these conditions.     

Triphenylphosphine-Catalyzed Michael Addition of Alcohols to Acrylic Compounds

A facile triphenylphosphine-catalyzed Michael addition of alcohols to acrylic compounds was described. The reaction was carried out in open air at refluxing temperature in the presence of 10 mol% PPh3. Michael addition of saturated and unsaturated alcohols to acrylonitrile or acrylates has been examined. The reaction gave β-alkoxy derivatives with isolated yields of 5%-79%. PPh3 is cheaper and more stable than those trialkylphosphines previously used for the similar reactions, and the products can be easily separated from the reaction mixture via distillation.     

Commercial Zinc Oxide (Zn2+) as an Efficient and Environmentally Benign Catalyst for Homogeneous Benzoylation of Hydroxyl Functional Groups

The solvent‐free O‐acylation of some alcohols with benzoyl chloride was carried out to the corresponding benzoylated products in good to excellent yields by the mediation of a catalytic amount (5 mol%) of the commercially available and inexpensive zinc oxide in short reaction times. This methodology represents an eco‐friendly and simple catalytic alternative for benzoylation of primary, secondary, tertiary, and benzylic alcohols with ZnO. This catalytic system was homogeneous because of high solubility of zinc oxide in the reaction medium. Findings showed that ZnO was dissolved in hydrochloric acid, created in situ, after a few minutes. Although, others argued on the catalytic role of solid phase zinc oxide under a heterogeneous condition, it is not surprising to emphasize on the catalytic function of Zn²⁺ in the benzoylation of alcohols under homogeneous reaction conditions. Zinc oxide served as pre‐catalyst to form Zn²⁺, as the catalytically active species.     

Triethylborane as an efficient promoter for palladium-catalyzed allylation of active methylene compounds with allyl alcohols

Without prior activation of allyl alcohols, allylation of a variety of active methylene compounds with allyl alcohols proceeds smoothly at rt-50°C in the presence of catalytic amounts of Pd(OAc)₂ (1-10 mol%), Et₃B (30-240 mol%), a phosphine ligand (1-20 mol%), and a base (0 to 50-60 mol%).     

Chemiluminescence Flow Injection Analysis of Menadione Sodium Bisulfite Based on Luminol Reaction

ABSTRACT

A chemiluminescence(CL) flow system is described for the determination of menadione sodium bisulfite based on its repression on the chemiluminescence(CL) emission produced upon mixing a hexacyanoferrate(III) solution with an alkaline luminol solution in the absence of co-oxidizer. The system responds linearly to menadione sodium bisulfite concentration in the range 0-1 μg/mL with a detection limit (3σ) of 0.01 μg/mL. Relative standard deviation (RSD) of 0.16% for 0.4 μg/mL menadione sodium bisulfite (n=11). The system has been successfully applied to the determination of menadione sodium bisulfite in tablets and injections.     

Graft polymerization of vinyl monomers onto cellulose in presence of soda lime glass. II

In the sodium bisulfite–soda lime glass initiating system, crude and true grafting yields increased with increasing ratio of methyl methacrylate to cellulose up to a limit; beyond this limiting value, grafting yields decreased due to the increase of the rate of sodium bisulfite-monomer addition over that of polymerization. Limitation was also achieved on increasing the glass to cellulose ratio through increased termination rates by coupling and disproportionation reactions, as the free radicals are increased. In addition, a limiting value was reached with increasing sodium bisulfite concentration; this may be related to the formation of a nonfunctioning disulfite ion at the expense of bisulfite radicals at high concentrations of sodium bisulfite. The temperature plays a role in this initiating system. Maximum rates of conversion and grafting were achieved at the ceiling temperature. Dissociation of the sodium bisulfite, which decreases with temperature, also has an effect.     

Nano–silica functionalized with thiol–based dendrimer as a host for gold nanoparticles: An efficient and reusable catalyst for chemoselective oxidation of alcohols

In this paper, we present the synthesis of Au nanoparticles supported on nanosilica thiol based dendrimer, nSTDP. The catalyst was prepared by reduction of HAuCl₄ with NaBH₄ in the presence of nSTDP. The resulting Au_np–nSTDP materials were characterized by FT–IR and UV–vis spectroscopic methods, SEM, TEM, TGA, XPS and ICP analyses. The characterization of the catalyst showed that Au nanoparticles with the size of 2–6 nm are homogeneously distributed on the nSTDP dendrimer with a catalyst loading of about 0.19 mmol/g of catalyst. The Au_np–nSTDP catalyst was used in the oxidation of alcohols with tert–butyl hydroperoxide (TBHP) as oxidant. The influence of vital reaction parameters such as solvent, oxidant and amount of catalyst on the oxidation of alcohols was investigated. These reactions were best performed in an acetonitrile/water mixture (3:2) in the presence of 0.76 mol% of the catalyst on the basis of the Au content at 80 °C under atmospheric pressure of air to afford the desired products in high yields (80–93% for benzyl alcohols). The Au_np–nSTDP catalyst exhibited a high selectivity toward the corresponding aldehyde and ketone (up to 100%). Reusabiliy and stability tests demonstrated that the Au_np–nSTDP catalyst can be recycled with a negligible loss of its activity. Also this catalytic exhibited a good chemoselectivity in the oxidation of alcohols.     

Sodium cyanide‐promoted copper‐catalysed aerobic oxidative synthesis of esters from aldehydes

A simple and efficient copper‐catalysed procedure for oxidative esterification of aldehydes with alcohols and phenols mediated by sodium cyanide, using air as a clean oxidant, is described. A variety of aromatic aldehydes and structurally different alcohols and phenols reacted efficiently, and the product esters were obtained in good to excellent yields under normal atmospheric and solvent‐free conditions.     

溴酸苄基三苯基膦的氧化性能研究

利用溴酸钠与氯化苄基三苯基膦作用得到溴酸苄基三苯基膦氧化剂。该氧化剂热稳定性好,氧化性能温和,在非质子有机溶剂中和在Lewis酸存在下,有效地将苄醇、环醇、和α-羟基酮氧化为相应的羰基化合物,产率较高;将苯硫酚氧化为二硫化物,产率中等。此外,对该氧化剂氧化烷基苯为醛、酮及羧酸,氧化芳醛为羧酸也作了研究。     

NaIO4/LiBr‐Mediated Direct Conversion of Benzylic Alcohols and Aromatic Aldehydes to Aromatic Esters

Aromatic aldehydes or benzylic alcohols are directly converted to the corresponding aromatic esters in high yields on treatment with methanol or ethanol mediated by sodium metaperiodate (NaIO₄)/LiBr in an acidic medium.     

Ligand-controlled phosphine-free Co(II)-catalysed cross-coupling of secondary and primary alcohols

Cobalt(II) complexes (5 mol% Co) bearing phosphine-free N^˄N^˄N pincer ligands efficiently catalyze C–C coupling of secondary and primary alcohols to selectively form α-alkylated ketones with a good functional group compatibility using NaOH (20 mol%) as a base at 120 °C. The NH group on the N^˄N^˄N–Co(II) precatalyst controls the activity and selectivity. This simple catalytic system is involved in the synthesis of quinolones via the dehydrogenative annulation of 2-aminobenzyl alcohols with secondary alcohols.     

乙酸促进邻甲基苯磺酸铜选择性催化醇和酚的四氢吡喃化反应

室温无溶剂条件下, 乙酸能有效促进邻甲基苯磺酸铜催化一系列醇或酚和3,4-2H-二氢吡喃反应, 生成相应的四氢吡喃醚. 在乙酸存在条件下, 体系的催化性能有显著提高, 邻甲基苯磺酸铜用量仅需0.3 mol%(占醇或酚的摩尔分数)就能使反应在较短时间内完成. 反应结束后, 邻甲基苯磺酸铜经简单相分离可多次重复使用, 催化活性无明显下降. 产物结构经IR, 1H NMR, 元素分析进行表征.     

醇类改性剂对胶束电动色谱分离的影响

胶束电动色谱（ＭＥＫＣ）是毛细管电泳常用的一种分离模式,它能使电中性化合物得到高效的分离．ＭＥＫＣ的分离度可通过调节电解质溶液的组成来提高．其中,有机改性剂的使用是近几年来ＭＥＫＣ研究的重点之一［１,２］．已有文献［３～５］报道以醇类作为电解质溶液的...     

Cu(II) bromide catalyzed oxidation of aldehydes and alcohols

A variety of aromatic, aliphatic and conjugated aldehydes and alcohols were transformed to the corresponding carboxylic acids and ketones with a quantitative conversion in high yields with 70% t‐BuOOH solution in water in the presence of catalytic (5 mol%) amounts of CuBr₂ under room temperature conditions. The conversion of 4‐methoxybenzaldehyde to 4‐methoxybenzoic acid is extremely facile in MeCN at ambient temperature in the presence of 5 mol% CuBr₂ and 2 equiv. 70% t‐BuOOH (water) as the oxidant. Oxidation with t‐BuOOH (water) alone in MeCN was found to be negligible. The scope of our catalytic system is applicable for a wide range of aromatic, conjugated and aliphatic substrates. These aldehydes were converted to the corresponding carboxylic acids in good isolated yields in reasonable times. It is pertinent to mention here that mild halogenic oxidants like hypochlorites, chlorites and NBS are not suitable for substrates with electron‐rich aromatic rings, olefinic bonds and secondary hydroxyl groups. Substitutions at different positions on the phenyl ring do not hinder the reaction, although the reaction time is affected. Oxidation of α,β unsaturated derivatives resulted in the formation of the expected acid in good yield. In addition, the transformation of secondary alcohols to ketones is extremely facile. No recemization was observed for menthone. This method possesses a wide range of capabilities since it can be used with other functional groups which may not tolerate oxidative conditions, involves fairly simple method for work‐up, exhibits chemoselectivity and proceeds under ambient conditions. The resulting products are obtained in good yields within reasonable time. Copyright © 2011 John Wiley & Sons, Ltd.     

Na促进的CuCoMn催化剂催化生物质合成气合成高醇

研究钠促进的CuCoMn催化剂的特性及其在生物质气化合成气合成高醇中的应用. 研究了催化剂中Na含量及合成条件(温度、压力和空速)对生物质基合成气合成高醇性能的影响. 发现CuCoMnNa_0.1催化剂较适合高醇合成, 在300 °C以下, 随着温度的上升, 碳转化率增大, 而醇选择性降低. 压力的增加有利于醇的合成, 增大空速会明显降低碳转化率, 但醇时空产率则因转换频率的增加而增大. 在所考察的范围内, 醇产率最高达到304.6 g·kg^-1·h^-1, 其中C₂₊高醇(C₂-C₆醇)占64.4% (w, 质量分数). 醇产物和烃产物均符合ASF (Anderson- Schulz-Flory)分布关系. 根据催化剂性能与表征分析, Na的加入有利于提高生物质气化合成气合成高醇的选择性和活性元素Cu、Co的分散性. X射线光电子谱(XPS)测试结果显示反应后的催化剂表面上, Cu以Cu⁺和Cu⁰的混合形式存在, 而Co则是Co²⁺/Co³⁺和Co⁰的混合物. 增加Na的含量, Cu⁰/Cu⁺比率和Co⁰的强度均随之减小.     

Heterocyclization of alicyclic 1,5-diketones. Synthesis of N-substituted 5-(4,5,6,7-tetrahydro-1H-indol-2-yl)pentanoic acids on the basis of (2,2'-methanediyl)biscyclohexanone and primary amines

Chemistry of Heterocyclic Compounds - The bisulfite adduct, formed upon treatment of (2,2'-methanediyl)biscyclohexanone with aqueos sodium bisulfite solution in the presence of acetic acid,...     

Enantioselective Reduction of Achiral Ketones with NaBH_4/I_2 Catalyzed by (S)-Ferrocenyl Amino Alcohols

In recent years much attention has been devoted to the enantioselective synthesis of optically active alcohols which are important starting materials for many biologically active compounds1. Since Corey and co-workers found the chiral oxazaborolidine catalyzed reduction (CBS reduction) of prochiral ketones, the method for the generation of chiral secondary alcohols has become one of the most attractive research fields2, 3. But borane and its complexes such as borane-THF or borane-dimethyl …