Low-valent ruthenium and iridium hydride complexes as alternatives to Lewis acid and base catalysts

The discovery of a new chemical reaction often leads to new applications and new chemical principles. Low-valent ruthenium and iridium hydride complexes are highly useful redox Lewis acid and base catalysts. Nitriles are activated by these catalysts and undergo reactions with either nucleophiles or electrophiles under neutral conditions. Hydration of nitriles, esterification of nitriles with alcohols, and amidation of nitriles with amines can be performed catalytically together with formation of ammonia. The catalytic reactions of pronucleophiles such as nitriles and carbonyl compounds with electrophiles such as alkenes, alkynes, carbonyl compounds, imines, and nitriles take place generally.     

Recovery of carbonyl compounds from N,N-dialkylhydrazones

Deprotonation of enantiomerically pure hydrazones and subsequent trapping with suitable electrophiles generates new stereogenic centers with excellent stereoselectivity. To liberate the original carbonyl functionality in the final products, it is necessary to cleave the hydrazone moiety. In recent years, many reagents have been developed to regenerate carbonyl compounds from the corresponding dialkylhydrazones which are compatible with a wide range of functionalities. This has allowed the use of hydrazones in the total synthesis of complex natural products. This Account is meant to be an overview of methods which are classified as oxidative, hydrolytic, and reductive cleavage procedures.     

软聚氯乙烯塑料的气味分析研究

采用气相色谱-质谱法(GC-MS)对3种软聚氯乙(烯S-PVC)试样的挥发性有机物进行了测试,分析了产生气味的物质。结果表明:试样产生的挥发性有机物为烃类化合物、醇和醛、酯等羰基化合物,产生气味的化合物主要是羰基化合物;添加抗氧剂可阻止增塑剂和其他烃类的氧化,减少S-PVC塑料气味的产生。     

气相色谱-质谱联用法测定软聚氯乙烯塑料的挥发性气体

采用气相色谱-质谱联用法,定性测定了软聚氯乙烯塑料（S-PVC）产生的挥发性气体。结果显示：软聚氯乙烯产生的挥发性气体主要为烃类化合物、醇和醛、酯等羰基化合物,产生气味的化合物是醇和羰基化合物,这些物质可由助剂带入或在塑料加工过程中热氧降解产生。     

车用聚丙烯复合材料气味分析研究

通过气相色谱-质谱对车用聚丙烯复合材料气味进行了分析研究.结果发现气味大的试样产生的挥发性有机化合物是羰基化合物与烃类化合物,而气味小的试样产生的多是烃类化合物,证明了产生气味的化合物是羰基化合物,如酮、醛与酯,这些物质是在高温加工过程中热氧降解产生的.     

芳基锡烷在有机合成中的应用

简要介绍了芳基锡烷的制备及其在有机合成中的应用。在温和条件下，芳基锡烷能和多种亲电试剂发生交叉偶联反应、羰基插入反应以及取代反应，并区域选择性和立体选择性地形成芳基衍生物。     

The Effect Of Preozonation On The Control Of Trihal Omethane Formation

A study was made to obtain a better understanding of the manner in which preozonation affects trihalomethane (THM) formation with respect to humic acid, citric acid, and 11 aromatic compounds which were components of humic acid, all in dilute aqueous medium. Ozonation before chlorination is able tonotonly decrease, butalso increase the concentrations of THM precursors. The compounds which are inherently high THM precursors, such as resorcinol, aniline, salicyl-aldehyde, phenol, andp-hydroxybenzoic acid, are controlled with respect tothe increase inthe amount ofozone consumed, but the compounds which have essentially no or alow potential for chloroform formation, such as hydroquinone. salicylic acid, methoxybenzene. benzaldehyde. and benzole acid, produce their maximum THM levels at a certain value of ozone consumed. When 1mg of organic carbon consumes more than 8 mg of ozone, THM formation from thetested aromatic compounds isdepressed by ozone.

Aliphatic carbonyl compounds which are the products resulting from the ozonation of aromatic compounds are not significant THM precursors. The preozonation of humic acid is not as effective in reducing its THM formation potential (THMFP) as when simple aromatic compounds are treated. However, the organic materials in the effluent from a biological treatment process usually have a high THMFP, in comparison with organic compounds which are contained in raw wastes. Therefore, there is a limitation in the effectiveness of utilizing biological treatment to remove the precursors of THM.     

On the Structure of Carbamoylated 2-Phenylaminopyridines

Unambiguous preparations of 2-(N-alkoxycarbonyl-N-phenyl)aminopyridine 1-oxides are used to prove that the product from 2-phenylaminopyridine 3 and phenyl isocyanate is the expected urea 2a . Recently a 1,2-dihydropyridine derivative 1 [4] has been claimed to be the product from 3 and phenyl isocyanate. The exocyclic nitrogen of 3 invariably reacts as the nucleophile towards electrophiles such as carbonyl chloride, esters of chloromethanoic acid and aryl isocyanates. ¹H n.m.r. and ¹³C n.m.r. spectra support the assigned structures of the products from these ractions.     

小桐子壳热解及其挥发性产物特性分析

选用小桐子壳作为原料,采用热重-红外联用(TG-FTIR)和热裂解-气相色谱质谱联用(Py-GC/MS)技术,研究小桐子壳的热解特性以及300~800℃热解过程中产物的组分信息和有机化合物中官能团随温度的变化情况,同时利用Coast-Redfern积分法求解不同升温速率下的动力学参数。结果表明,小桐子壳的热解过程分为干燥(30~100℃)、预热解(100~258℃)、热解(258~420℃)和炭化(420~900℃)四个阶段。随升温速率升高,小桐子壳的最大质量损失率依次增加,升温速率的升高对小桐子壳热分解速率具有促进作用。随热解温度升高,吸收峰处存在明显的强度变化,CO2、醛酮类等化合物的吸收峰强度逐渐降低甚至消失;小桐子壳热解过程中的气体产物成分主要为CO, CO2, H2O等,主要挥发性有机产物为苯酚、羰基化合物、愈创木酚类等,热解温度由400℃升至700℃时,酚类化合物的峰面积比例从35.94%升至59.59%、羰基化合物的峰面积比例从36.90%降到11.87%。小桐子壳热解动力学参数n=1时,其反应表观活化能最大为61.34 kJ/mol,且三个升温速率的拟合相关系数均在98%以上。小桐子壳热解动力学参数n≠1时,选取相关系数最大时的n值为反应级数,则n=0.2,反应活化能E为47.64 kJ/mol,指数前因子A为0.83。随升温速率的升高表观活化能依次递减,且拟合相关系数均在97%以上。     

Fingerprinting of fatty acid composition for the verification of the identity of organic eggs

Organic products (such as organic eggs) usually have a higher price than the corresponding conventional products. This makes organic products susceptible to fraud. Administrative controls are conducted to detect this type of frauds. However, an analytical verification of the organic identity of food products would be very useful in this respect. It is unlikely that there is a single compound, or a few compounds, that differ sufficiently between organic and conventional eggs to be used as a marker of organic identity. Instead, fingerprinting of the organic products (that is to say, analyzing a wide range of compounds instead of only a few) might be used as a tool for their verification. Here, we have used the fatty acid composition of egg yolks as a fingerprint to verify the organic identity of eggs. From the fingerprints, chemometric models were built which predict the identity of eggs (organic or conventional) with high success rates.     

Characterization of water-soluble cellulose derivatives produced by alkali treatment of ozonized allylated celluloses

Ozonization products of allylated celluloses such as completely allylated methylcellulose and tri-O-allylcellulose, which are insoluble in both organic solvents and water, gave water-soluble derivatives by alkaline treatment. Infrared (IR) and ¹³C-NMR (nuclear magnetic resonance) spectrometries revealed that the products have many carboxyl as well as carbonyl groups. Allyl ethers in allylated celluloses were found to be cleaved by 30–35% during ozonization, whereas alkyl ethers such as methyl and ethyl ethers in cellulose derivatives were completely stable.     

N-烷基芳胺合成的研究进展

N-烷基芳胺是非常重要的有机原料和精细化工中间体,广泛应用于染料、塑料、医药和农药等领域。介绍了芳胺与烷基化试剂如卤代烃、羰基化合物、醇等进行的取代烷基化反应合成N-烷基芳胺的反应机理及烷基化工艺;重点阐述了以芳香硝基化合物为原料一锅法合成N-烷基芳胺的生产工艺,分别讨论了以羰基化合物、腈、醇作为烷基化试剂的优劣,认为以醇为烷基化试剂的反应条件温和、不需要添加任何配体,具有较好的应用前景。指出开发适合以醇为烷基化试剂的选择性高的催化剂是以后的研究方向。     

Versatile electrochemically based preparation of unusual Grignard reagents containing electrophilic substituents

Upon electrochemical reduction of potassium perchlorate in dimethyl sulfoxide to potassium the strong dimsyl base (i.e. the conjugate base of dimethyl sulfoxide) is formed in the reaction of the alkali metal with the solvent. The electrolysis is performed in an undivided cell with a magnesium rod serving as sacrificial anode, thereby generating magnesium ions, which stabilize the generated dimsyl through ion-pair formation. In a second non-electrochemical step, Grignard type reagents R₂Mg are obtained simply by letting the magnesium salt of dimsyl base deprotonate weakly acidic substrates (pK_a < 26 in dimethyl sulfoxide) added to the solution. The advantage of generating these reagents through a deprotonation route rather than by reduction of halogen-substituted compounds as in the classical approach is that the substrates may contain electrophilic groups, such as halogen, carbonyl or cyano. The R₂Mg reagents react with electrophiles akin to ordinary Grignard reagents as illustrated by the preparation of several substituted benzylidenefluorenes in nucleophilic addition reactions. The electrochemical properties of the products were investigated and a reasonable linear correlation of the first reduction potentials with the Hammett substituent coefficient σ⁻ was found.     

Low-Oxidation State Indium-Catalyzed C-C Bond Formation

The development of innovative metal catalysis for selective bond formation is an important task in organic chemistry. The group 13 metal indium is appealing for catalysis because indium-based reagents are minimally toxic, selective, and tolerant toward various functional groups. Among elements in this group, the most stable oxidation state is typically +3, but in molecules with larger group 13 atoms, the chemistry of the +1 oxidation state is also important. The use of indium(III) compounds in organic synthesis has been well-established as Lewis acid catalysts including asymmetric versions thereof. In contrast, only sporadic examples of the use of indium(I) as a stoichiometric reagent have been reported: to the best of our knowledge, our investigations represent the first synthetic method that uses a catalytic amount of indium(I). Depending on the nature of the ligand or the counteranion to which it is coordinated, indium(I) can act as both a Lewis acid and a Lewis base because it has both vacant p orbitals and a lone pair of electrons. This potential ambiphilicity may offer unique reactivity and unusual selectivity in synthesis and may have significant implications for catalysis, particularly for dual catalytic processes. We envisioned that indium(I) could be employed as a metallic Lewis base catalyst to activate Lewis acidic boron-based pronucleophiles for selective bond formation with suitable electrophiles. Alternatively, indium(I) could serve as an ambiphilic catalyst that activates both reagents at a single center. In this Account, we describe the development of low-oxidation state indium catalysts for carbon-carbon bond formation between boron-based pronucleophiles and various electrophiles. We discovered that indium(I) iodide was an excellent catalyst for α-selective allylations of C(sp(2)) electrophiles such as ketones and hydrazones. Using a combination of this low-oxidation state indium compound and a chiral semicorrin ligand, we developed catalytic highly enantioselective allylation, crotylation, and α-chloroallylation reactions of hydrazones. These transformations proceeded with rare constitutional selectivities and remarkable diastereoselectivities. Furthermore, indium(I) triflate served as the most effective catalyst for allylations and propargylations of C(sp(3)) electrophiles such as O,O-acetals, N,O-aminals, and ethers, and we applied this methodology to carbohydrate chemistry. In addition, a catalyst system composed of indium(I) chloride and a chiral silver BINOL-phosphate facilitated the highly enantioselective allylation and allenylation of N,O-aminals. Overall, these discoveries demonstrate the versatility, efficiency, and sensitivity of low-oxidation state indium catalysts in organic synthesis.     

有机合成中二芳基碘（Ⅲ）盐的应用

综述了二芳基碘（Ⅲ）盐在金属催化的交叉偶联反应、羰基化合物的a-芳基化、炔烃的芳基化、杂原子亲核化合物的芳基化等反应中的应用。     

Role of Nitric Oxide-Derived Metabolites in Reactions of Methylglyoxal with Lysine and Lysine-Rich Protein Leghemoglobin

Carbonyl stress occurs when reactive carbonyl compounds (RCC), such as reducing sugars, dicarbonyls etc., accumulate in the organism. The interaction of RCC carbonyl groups with amino groups of molecules is called the Maillard reaction. One of the most active RCCs is α-dicarbonyl methylglyoxal (MG) that modifies biomolecules forming non-enzymatic glycation products. Organic free radicals are formed in the reaction between MG and lysine or Nα-acetyllysine. S-nitrosothiols and nitric oxide (^•NO) donor PAPA NONOate increased the yield of organic free radical intermediates, while other ^•NO-derived metabolites, namely, nitroxyl anion and dinitrosyl iron complexes (DNICs) decreased it. At the late stages of the Maillard reaction, S-nitrosoglutathione (GSNO) also inhibited the formation of glycation end products (AGEs). The formation of a new type of DNICs, bound with Maillard reaction products, was found. The results obtained were used to explain the glycation features of legume hemoglobin—leghemoglobin (Lb), which is a lysine-rich protein. In Lb, lysine residues can form fluorescent cross-linked AGEs, and ^•NO-derived metabolites slow down their formation. The knowledge of these processes can be used to increase the stability of Lb. It can help in better understanding the impact of stress factors on legume plants and contribute to the production of recombinant Lb for biotechnology.     

Formation of C-C Bonds via Ruthenium Catalyzed Transfer Hydrogenation: Carbonyl Addition from the Alcohol or Aldehyde Oxidation Level

Under the conditions of ruthenium catalyzed transfer hydrogenation employing isopropanol as terminal reductant, π-unsaturated compounds (1,3-dienes, allenes, 1,3-enynes and alkynes) reductively couple to aldehydes to furnish products of carbonyl addition. In the absence of isopropanol, π-unsaturated compounds couple directly from the alcohol oxidation level to form identical products of carbonyl addition. Such "alcohol-unsaturate C-C couplings" enable carbonyl allylation, propargylation and vinylation from the alcohol oxidation level in the absence of stoichiometric organometallic reagents or metallic reductants. Thus, direct catalytic C-H functionalization of alcohols at the carbinol carbon is achieved.     

有机相微生物活细胞催化羰基不对称还原反应的研究进展

介绍了近１０年来在有机介质中以微生物活细胞作为生物催化剂催化羰基化合物不对称还原反应的最新进展,分析了有机相中影响微生物催化及立体选择性的因素,并列举了一些反应实例。     

金属催化羰基化合物还原偶联反应的研究进展

羰基化合物还原偶联反应是形成碳一碳键最有效的方法之一,在有机合成中占有重要地位。羰基化合物还原偶联通常由羰基化合物与相应的金属试剂或金属络合物作用而实现,一般遵循单电子转移历程。本文综述了近年来金属钛、钐、铬等在羰基化合物还原偶联反应中应用的新进展。     

Copper, silver, and gold complexes in hydrosilylation reactions

The reduction of diverse functional groups is an essential protocol in organic chemistry. Transition-metal catalysis has been successfully applied to the reduction of olefins, alkynes, and many carbonyl compounds via hydrogenation or hydrosilylation; the latter presenting several advantages over hydrogenation. Notably, hydrosilylation generally occurs under mild reaction conditions, and consequently over-reduced products are rarely detected. Moreover, the great majority of hydrosilanes employed in this reaction are easily handled, inexpensive, or both. A large number of multiple bonds can be involved in this context, and the hydrosilylation reaction can be regarded as a useful method for the synthesis of silicon-containing organic molecules or a convenient way of reducing organic compounds. Furthermore, the silyl group can also be retained as a protecting group, a strategy that can be of great usefulness in organic synthesis. Since the first Wilkinson's catalyst-mediated hydrosilylation of ketones in 1972, metals such as rhodium and iridium have attracted most of the attention in this area. A wide array of catalytic systems for hydrosilylation reactions is nowadays available, which has allowed for a great expansion of the synthetic scope of this transformation. After having been overlooked in the early years, group 11 metals (Cu, Ag, and Au), especially copper, have emerged as appealing alternatives for hydrosilylation. The use of a stabilized form of copper hydride, the hexameric [(Ph3P)CuH]6, by Stryker represented a breakthrough in copper-catalyzed reduction reactions. Nowadays, several copper-based catalytic systems compare well with a variety of reported rhodium-based catalysts, which generally suffer from the high cost of the catalyst. Tertiary phosphine ligands are the most widely used in these transformations. However, other families such as N-heterocyclic carbenes (NHCs) have shown promising activities. Compared with copper, little attention has been paid to silver- or gold-based catalysts. Silver salts have been considered inert towards hydrosilylation, and they are often employed as innocent anion exchange reagents for the in situ generation of cationic transition metal catalysts. Despite the rare reports available, they have already shown interesting reactivity profiles, for example, in the chemoselective reduction of aldehydes in the presence of ketones. Furthermore, 1,2-hydride delivery is favored over 1,4-reductions for alpha,beta-unsaturated carbonyl compounds, in contrast with most copper-based systems.