A novel three-component butenolide synthesis

[reaction: see text]. 5-Acylamino butenolides can be assembled by a multicomponent reaction (MCR) of isocyanides, glyoxals, and acetophosphonic acid diethylesters, followed by a intramolecular Wittig-type reaction. The reaction can be performed either in one pot or with the isolation of the intermediate Passerini product. This versatile reaction offers three independent inputs displayed in the final product. Applications in combinatorial chemistry and natural product synthesis can be envisioned.     

A novel catalytic decarbonylative Heck-type reaction and conjugate addition of aldehydes to unsaturated carbonyl compounds

A novel rhodium-catalyzed decarbonylative reaction of aldehydes with unsaturated carbonyl compounds was discovered to generate Heck-type reaction product and conjugate addition product.     

Chemistry of the phenoxathiins and isosterically related heterocycles. XVII. First synthesis of a benzoxathiinopyridazine and the determination of structure by 13C-NMR: 1-Methoxy-3,4-diazaphenoxathiin

The reaction of 5-methoxy-3,4-dichloropyridazine with the disodium salt of o-mercaptophenol leads to the formation of 1-methoxy-3,4-diazaphenoxathiin as the sole product of the reaction. The structure of the isolated product was confirmed by ¹³C-nmr spectroscopy, with the development of arguments to discriminate the isolated compound from 4-methoxy-1,2-diazaphenoxathiin, the other product possible in this reaction. Mechanistic considerations in the formation of the isolated product are discussed.     

DNA的滚环扩增合成研究

滚环扩增(RCA)反应作为一种简单高效的等温酶促反应,现已发展为核酸扩增领域的新技术,其产物在组装体搭建和多功能材料的制备方面有着广泛的应用。本文采用琼脂糖凝胶、紫外和透射电镜(TEM)等手段,探究了时间、三磷酸脱氧核糖核苷(dNTPs)、酶以及引物的浓度等因素对脱氧核糖核酸(DNA)滚环扩增产物的影响。结果表明:在反应开始的前30 min,RCA产物的长度受时间的影响比较明显;随着dNTPs浓度的提高,RCA产物的链长增长,浓度也不断提高;酶和引物的浓度对滚环扩增产物的长度没有明显影响,但对RCA产物浓度的影响较大,过量的酶致使RCA产物的含量显著下降。     

Specific features of the chemical reaction of carbonyl groups with hydrazine accosting to the data of X-ray photoelectron spectroscopy

The reaction of hydrazine vapor with surface carbonyl groups was used for the quantitative determination of functional groups of organic polymers. The specific features of this reaction were studied using poly(vinyl methyl ketone) as an example. It was shown by X-ray photoelectron spectroscopy that the main reaction product at the initial stage is hydrazinecarbinol, which is then consecutively converted to hydrazone and azine. The results of calculations predict that virtually the only reaction product is azine. It was shown that the wrong identification of the reaction product has lead to the distortion of the results of analysis.     

Nonadiabatic reactant-product decoupling calculation for the F(2P(1/2)) + H2 reaction

In this paper we present a theoretical study using time-dependent nonadiabatic reactant-product decoupling method for the state-to-state reactive scattering calculation of F((2)P(1/2))+H(2) (nu=j=0) reaction on the Alexander-Stark-Werner potential energy surface. In this nonadiabatic state-to-state calculation, the full wave function is partitioned into reactant component and a sum of all product components. The reactant and product components of the wave function are solved independently. For the excited state reaction, the state-to-state reaction probabilities for J=0.5 are calculated. Comparing the state-to-state reaction probabilities, it is found that the vibrational population of the HF product is dominated by vibrational levels nu=2 and 3. The rotation specific reaction probabilities of HF product in j=1 and 2 are larger than those in other rotational levels. As the rotation quantum number j increases, the positions of the peak in the rotational reaction probability of HF product in nu=3 shift to higher collision energy.     

C_（60）的胺加成反应和电喷雾电离质谱（ESI－MS）检测

报道了Ｃ６０与１，３－丙二胺和Ｎ，Ｎ－二甲基－１，３－丙二胺的加合反应，反应产物未经预先离子化处理直接用ＥＳＬ－ＭＳ进行检测。由于反应产物从甲苯溶液中析出，避免了生成多胺基加合物，产物以单加成物为主。当加合反应在空气氛下进行时，有加合氧的产物Ｃ６０Ｏｎ（ＮＨ２—ＣＨ２ＣＨ２ＣＨ２ＮＲ２）ｍ（Ｒ＝Ｈ，ＣＨ３）存在。实验发现：Ｎ，Ｎ－二甲基－１，３－丙二胺比１，３－丙二胺更容易与Ｃ６０发生多胺基加成和氧加成反应。通过控制反应条件可制备Ｃ６０二胺的单加成产物。     

Surface structural information carried by desorbing reaction products

Recent progress in angle-resolved measurements of desorbing surface reaction products is reviewed. The angular and velocity distributions of desorbing products with hyper-thermal energy deliver the most direct structural information of the product formation site. These distributions yield the orientation of the intermediate species emitting the product as well as the shape of the product formation site. This method works well even when the overall reaction rate is controlled by reactant adsorption or when the interaction between adsorbed species is obscured in kinetic studies under steady-state conditions. For its application, however, information about the reaction mechanism is requisite because the method is directly linked to the reaction itself. Analysis of the product emission in NO reduction on palladium and rhodium as well as the product formation site and its switchover in CO oxidation on platinum is exemplified.     

Enzyme-catalyzed reaction of OPD-H_2O_2-HRP voltammetric enzyme-linked immunoassay system

Ｈｏｒｓｅｒａｄｉｓｈｐｅｒｏｘｉｄａｓｅ(ＨＲＰ)ｃａｎｓｔｒｏｎｇｌｙｃａｔａｌｙｚｅｔｈｅｒｅａｃｔｉｏｎｏｆＨ2Ｏ2ｏｘｉｄｉｚｉｎｇｏｐｈｅｎｙｌｅｎｅｄｉａｍｉｎｅ(ＯＰＤ),ｔｈｅｃｈｒｏｍａｔｉｃｐｒｏｄｕｃｔｏｆｗｈｉｃｈｃａｎｂｅｄｅｔｅｃｔｅｄｉｎｅｎｚｙｍｅｌｉｎｋｅｄｉｍｍｕｎｏｓｏｒｂｅｎｔａｓｓａｙ(ＥＬＩＳＡ)ｗｉｔｈｓｐｅｃｔｒｏｐｈｏｔｏｍｅｔｒｙ[1].Ｉｎｖｏｌｔａｍｍｅｔｒｉｃｅｎｚｙｍｅｌｉｎｋｅｄｉｍｍｕｎｏａｓｓａｙ[2—4],ＯＰＤＨ2Ｏ2ＨＲＰｓｙｓｔｅｍｈａｓｆ…     

Reaction Between Copper Nitrate Hydrate and Methoxydimethyloctylsilane in Methanol

The reaction rate was determined for copper nitrate hydrate with methoxydimethyloctylsilane (MDOS) in methanol. The rate constants of hydrolysis and condensation were established by quantitative measurement of the product and Karl Fischer water determination. The reaction with the hydrated copper salt resulted in the phase separation of an insoluble product from the reaction mixture. The structure of the product was determined, by Fourier Transform Infrared Spectrometry (FTIR) and Nuclear Magnetic Resonance (NMR) to be a dimer of the MDOS. The results showed the alcohol, producing condensation reaction was negligible in the formation of the dimer. contrary to the case for the well-known reaction by trialkoxysilanes and tetraalkoxysilanes.     

钒酸铋颜料制备实验的改进——pH优化

使用改进的实验装置研究钒酸铋颜料制备实验中p H对产物的影响。X射线衍射分析结果表明,在选定实验条件下,产物为四方相为主的四方、单斜两相混合物。p H对钒酸铋颜色有重要影响。酸性条件下颜色偏深,为土黄色;碱性条件下为亮黄色,且p H越大,颜色越淡。推荐反应p H为9,此时产物颜色呈色调较好的亮黄色。     

A Closer Look at Spontaneous Mirror Symmetry Breaking in Aldol Reactions

The aldol reaction between acetone and 4‐nitrobenzaldehyde run in the nominal absence of any enantioselective catalyst was monitored by chiral HPLC with the aid of an internal standard. The collected data show the presence of a detectable initial enantiomeric excess of the aldol product in the early stages of the reaction in about 50 % of the experiments. Only a small fraction of the reaction contained the non‐racemic aldol product after 24 h. This temporary emergence of natural optical activity could be the signature of a coupled reaction network that leads to a spontaneous mirror‐symmetry‐breaking process, which originates at very low conversions (i.e., strongly depends on events taking place at the very first stages of the process). The reaction is not autocatalytic in the aldol product, which rules out a simple Frank‐type reaction network as the source of the observed symmetry breaking. On the other hand, the isolation and characterisation of a double‐aldol adduct suggested a reaction network that involved both indirect autocatalysis and indirect mutual inhibition between the enantiomers of the reaction product.     

硝基烷基膦酸酯碳负离子烷基化反应区域选择性研究

α-或β-硝基烷基膦酸酯双负离子与卤代烷反应, 生成碳-烷基化产物, 反应区域选择性取决于硝基膦酸酯的结构, 讨论了可能的反应机理。     

An Upstream By‐product from Ester Activation via NHC‐Catalysis Catalyzes Downstream Sulfonyl Migration Reaction

A sequential reaction combining N‐heterocyclic carbene (NHC) and N‐hydroxyphthalimide (NHPI) catalysis allowed for the upstream by‐product NHPI, which was generated in the NHC‐catalyzed cycloaddition reaction, to act as the catalyst for a downstream nitrogen‐to‐carbon sulfonyl migration reaction. Enantiomeric excess of the major product in the cycloaddition reaction remained intact in the follow‐up sulfonyl migration reaction.     

Single-ion recycling reactions

A single ion is enough: Ion reaction rates and reaction product branching ratios could be determined through repeated regeneration of the original target ion by photodissociation after each reaction. The product molecule was identified through nondestructive mass spectrometry. Finally, the target ion was regenerated through photodissociation of the molecular ion.     

Diastereo‐ and Enantioselective 1,4‐Difunctionalization of Borylenynes by Catalytic Conjunctive Cross‐Coupling

Enantioselective conjunctive cross‐coupling of enyne‐derived boronate complexes occurs with 1,4 addition of the electrophile and migrating group across the π system. This reaction pathway furnishes α‐boryl allenes as the reaction product. In the presence of a chiral catalyst, both the central and axial chirality of the product can be controlled during product formation.     

Synthetic applications of ethyl 3-bromodifluoromethyl-3-benzyloxy-acrylate as a gem-difluorination building-block: Its reactions with aldehyde and epoxide

Synthetic applications of ethyl 3-bromodifluoromethyl-3-benzyloxy-acrylate as a versatile and multifunctionalized gem-difluorination building block to introduce difluoromethene subunit into some new hydroxy esters have been investigated. It was found that its zinc mediated reaction with a variety of aldehyde in DMF gave the Reformatsky reaction mode product, β-hydroxy ester, in good yield, while its tetrakis(dimethylamino)ethylene (TDAE) promoted reaction with a limited scope of aldehyde produced Barbier reaction mode product, δ-hydroxy ester, in moderate yield. The reaction of its zinc reagent with styrene oxide resulted in rearrangement of the epoxide to 2-phenyl-acetaldehyde, and then the zinc reagent condensed with this aldehyde to provide the Reformastsy reaction type product, β-hydroxy ester, in low yield.     

Tandem intramolecular Michael-aldol reaction as a tool for the construction of the C-ring of hexacyclinic acid

[reaction: see text] The tandem intramolecular Michael-aldol reaction was studied as a tool for the construction of the C-ring of hexacyclinic acid. By changing the reaction conditions it was possible to selectively obtain either the kinetic or the thermodynamic product. Retro-aldol reaction and subsequent epimerization provides four individual cyclopentane derivatives that can be incorporated as building blocks in natural product syntheses.     

Asymmetric autocatalysis: product recruitment for the increase in the chiral environment (PRICE)

Asymmetric catalytic reactions are possible via efficient transfer of the chiral environment of a reaction to the transition state. In theory any asymmetric structure may contribute to this, including the product of the reaction itself. For product influence to be significant, a nonlinear effect needs to operate, whereby one diastereomer of the product/catalyst assists the reaction, and the other does not. When these conditions are satisfied, we obtain an asymmetric autocatalytic reaction in which the enantiomeric excess of a compound (that is both product and catalyst) actually increases as the reaction iterates. It is only recently that we have seen reports of such processes. Of particular interest are Soai's reports of the alkylation of aromatic heterocycles. Such reactions, aside from their inherent interest, may offer clues into the origins of asymmetric molecular replication that predated the origin of life.     

Modeling Nd-Catalyzed Butadiene Rubber Production

Summary: A simulation tool was developed for the industrial solution polymerization of 1,3-butadiene with a Nd-based homogeneous Ziegler-Natta catalyst system. Insight into underlying reaction mechanisms was gained from laboratory experiments. Besides the chain growth reaction, the following steps were identified: catalyst formation, deactivation reactions, and molecular weight control reactions. A kinetic model based on this reaction scheme was developed to quantitatively describe butadiene conversion and product molecular weight distribution. By including process characteristics, the laboratory (batch) model was transferred to the industrial production process. A correlation function relates product molecular weight to the relevant product property Mooney viscosity. This polymerization model was successfully applied, e.g. to optimize product grade transitions and to maintain high product quality by predicting the influence of process changes.