超声辐射与相转移催化结合方法产生二氯卡宾

超声辐射和相转移催化相结合可以有效地促进自氯仿产生二氯卡宾的反应, 该方法具有速度快、产率高、催化剂用量少等优点, 是一种产生二氯卡宾的新的实用方法.     

相转移催化反应研究__二卤卡宾加成反应

自从Makosza等发现鎓翁盐化合物作为相转移催化剂以来,十余年来相转移催化(PTC)已广泛应用于有机合成领域。Dehmlow等对相转移催化剂的催化效率及二氯卡宾与脂肪烯烃反应的动力学作过一些探讨。     

相转移催化反应研究 II.相转移催化产生的二卤卡宾的环加成反应动力学研究

本文研究了在50%NaOH,CH~2Cl~2体系中相转移催化产生的二氯及二溴卡宾与对位取代的苯乙烯反应的相对速率常数k~rel并用Brown式进行了线性相关分析。在此条件下,二氯及二溴卡宾都是有亲电性,其中二氯卡宾的选择性大于二溴卡宾。本文还测定了上述相转移反应中,反应物烯烃、溴仿浓度随时间变化的情况,并用动力学公式对所得的曲线进行了分析,得出在此条件下,反应为二级,其中对烯烃和溴仿各为一级,溴仿过量时,反应对烯烃呈准一级。     

相转移催化反应研究 Ⅱ.相转移催化产生的二卤卡宾的环加成反应动力学研究

本文研究了在50％NaOH,CH_2Cl_2体系中相转移催化产生的二氯及二溴卡宾与对位取代的苯乙烯反应的相对速率常数k_(rel),并用Brown式(lgk_(rel)=lgk_0+σ~+P~+)进行了线性相关分析.在此条件下,二氯及二溴卡宾都具有亲电性,其中二氯卡宾的选择性大于二溴卡宾.本文还测定了上述相转移反应中,反应物烯烃、溴仿浓度随时间变化的情况,并用动力学公式对所得的曲线进行了分析,得出在此条件下,反应为二级,其中对烯烃和溴仿各为一级.溴仿过量时,反应对烯烃呈准一级.     

卡宾的钨配合物与二氯甲基Wittig试剂的反应

本文报导了用卡宾的钨配合物进一步用于与二氯甲基Wittig试剂的反应, 合成1,1-二氯-2-烷氧基烯烃。1,1-二卤代烯烃是一类产生不饱和卡宾的前体化合物。本文旨在通过对卡宾的钨配合物与二氯代Wittig试剂之间的反应研究, 进一步研究烷氧基取代不饱和卡宾的性质。     

卡宾的钨配合物与二氯甲基Wittig试剂的反应

卡宾的过渡金属配合物是一个十分活跃的研究领域,有关它们的制备方法及性质的研究工作正日益引起人们的注意。Burkhardt等发现,卡宾的钨配合物能与Witting试剂反应,生成烷氧基取代烯烃。本文将卡宾的钨配合物进一步用于与二氯甲基Wittig试剂的反应,合成1,1-二氯-2-烷氧基烯烃。众所周知,1,1-二卤代烯烃是一类产生不饱和卡宾的前体化合物。因此,通过对卡宾的钨配合物与二氯代Wittig试剂之间的反应研究,还可以为进一步研究烷氧基取代不饱和卡宾的性质提供方便。     

微波场中二氯卡宾产生的研究

二氯卡宾是应用最为广泛的活性中间体,早期制备二氯卡宾的方法为氯仿与叔丁醇钾等强碱作用,条件苛刻。一直到1969年Makosza和Wawrzyniewicz的著名论文发表后,用强碱水溶液和相转移催化剂制取二氯卡宾被认为是最简捷的方法。另据文献报道,以聚氧乙烯类表面活性剂作催化剂进行固-液相反应制备二氯卡宾也可获得较理想的结果。但广泛的实     

四氯化碳与镁的反应及其反应机理的研究──产生二氯卡宾的新方法

四氯化碳与镁的反应及其反应机理的研究──产生二氯卡宾的新方法林海霞,徐良衡,黄乃聚（温州师范学院化学系,温州,３２５００３）（复旦大学化学系）关键词二氯卡宾,偕二氯环丙烷衍生物,单电子转移偕二氯环丙烷衍生物是一类重要的有机合成中间体,它主要通过二氯卡...     

超声波作用下偕二卤环丙烷与金属反应机理的探讨

在超声波辐射下,偕二卤环丙烷化合物与金属锂或镁迅速反应,产生三员环卡宾中间体,并可用烯烃捕获。对所有反应产物分析鉴定后证实,反应经单电子转移,首先产生游离基中间体,它进一步得到电子产生卡宾,随之发生插入、加成或重排反应;也能夺取溶剂分子的氢原子生成单卤代产物,并进一步生成相应的环丙烷化合物。本文对反应结果及其机理进行了讨论。     

二氯卡宾与烯丙基硅化合物的加成

关于二氯卡宾与烯烃基硅化合物加成反应的研究,迄今只有 Cudlin 等所发表的论文。他们使氯仿和叔丁醇钾作用得到的二氯卡宾与烯烃基三甲基硅烷进行亲电子加成,合成三甲硅烷基二氯环丙烷衍生物,并曾研究三甲硅烷基对处于不同位置上双键加成速率的影响。     

Catalytic Asymmetric Hetero-Diels-Alder Reactions of Carbonyl Compounds and Imines

Asymmetric catalysis is a challenge for chemists: How can we design catalysts to achieve the goal of forming optically active compounds? This review provides the reader with an overview of the development of catalytic asymmetric hetero-Diels-Alder reactions of carbonyl compounds and imines. Since its discovery, the Diels-Alder reaction has undergone intensive development and is of fundamental importance for synthetic, physical, and theoretical chemists. The Diels-Alder reaction has been through different stages of development, and at the beginning of the 21st century catalytic Diels-Alder reactions are one of the main areas of focus. The preparation of numerous compounds of importance for our society is based on cycloaddition reactions to carbonyl compounds and imines. There are several parallels between the reactions of carbonyl compounds and those of imines, which, however, begin to vanish on entering the field of catalytic reactions. Why? From a mechanistic point of view some similarities can be drawn, but the synthetic development of catalytic enantioselective hetero-Diels-Alder reactions of imines are several years behind those of the carbonyl compounds. For hetero-Diels-Alder reactions of carbonyl compounds there a number of different chiral catalysts, and great progress has been achieved in developing enantioselective reactions for unactivated and activated carbonyl compounds. In contrast the development of catalytic enantioselective hetero-Diels-Alder reactions of imines is in its infancy and only few catalytic reactions have been published. This review will focus on the most important developments, and discuss the synthetic and mechanistic aspects of enantioselective hetero-Diels-Alder reactions of carbonyl compounds catalyzed by chiral Lewis acids. For the hetero-Diels-Alder reactions of imines, the diastereoselective reactions of optically substrates catalyzed by Lewis acids will be presented first, followed by the catalytic enantioselective reactions.     

Perspective on dirhodium carboxamidates as catalysts

Dirhodium compounds are emerging as highly efficient catalysts for diverse reactions, and those with carboxamidate ligands have the broadest applications. The unique features of these compounds are their structural rigidity, ease of ligand exchange, open diaxial sites for coordination with Lewis bases, and their low oxidation potential. As consequences of this, dirhodium carboxamidates are efficient and effective catalysts for metal carbene reactions, Lewis acid-catalyzed processes, and chemical oxidations. With chiral carboxamidate ligands these dirhodium compounds show exceptional enantiocontrol for intramolecular cyclopropanation and carbon-hydrogen insertion reactions of diazoacetates, and they are also highly efficient and selective for hetero-Diels-Alder reactions. Their limitations lie in their moderate reactivities for metal carbene generation and Lewis acid catalysis and in the cost of the precious metal rhodium.     

Die Chemie der Pyrrole : by A. Gossauer,Springer-Verlag,Berlain/Heidelberg/-New York, 1974, xx + 433 PP., DM158

Reaction mechanisms and solvent effects of reactions of cis-(CH₃)₂ IAuPPh₃ compounds with labeled alkylgold(I) complexes are discussed; the results are compared with those of reactions of similar mercury compounds.     

Preparation,Structure, and Reactions of Halomalondialehdes

The present progress report provides a survey of the synthesis, structure, and reactions of halomalondialdehydes, including “cyanomalondialdehyde” (diformylacetonitrile), the only pseudohalogen compound so far known in this series. Halomalondialdehydes are reactive compounds, applicable in a variety of ways, and are characterized particularly by their cyclizations with bifunctional compounds. Many of the reactions discussed below can be applied to substituted malondialdehydes other than those specified.     

Synthesis and reactions of rhodium compounds containing tellurium donor ligands

This paper describes the synthesis and characterization of a series of rhodium(I) and rhodium(III) complexes containing tellurium-rhodium bonds resulting from the coordination of diorgano telluride or organotelluro ligands. Oxidative addition, metathesis and substitution reactions of these compounds have been examined, and the resulting products are compared with those from the known reactions of rhodium(I) and rhodium(III) compounds containing phosphine ligands.     

Exploration of mid-temperature alkali-metal-ion extraction route using PTFE (AEP): transformation of α-NaFeO2-type layered oxides into rutile-type binary oxides

Alkali-metal-ion extraction reactions using poly(tetrafluoroethylene) (PTFE; AEP reactions) were performed on two kinds of α-NaFeO(2)-type layered compounds: Na(0.68)(Li(0.68/3)Ti(1-0.68/3))O(2) and K(0.70)(Li(0.70/3)Sn(1-0.70/3))O(2). At 400 °C in flowing argon, these layered compounds were reacted with PTFE. By these reactions, alkali-metal ions in the layered compounds were successfully extracted, and TiO(2) and SnO(2) with rutile-type structure were formed. The structural similarity between the alkali-metal-ion-extracted layered compounds and the binary metal oxide products in these unique alkali-metal-ion extraction reactions was interpreted in terms of their interatomic distance distribution by atomic pair distribution function analysis. The results of this study indicate that PTFE is an effective agent to extract alkali-metal ions from layered compounds, and AEP reaction is not limited to the previously reported γ-FeOOH-type layered titania K(0.8)(Li(0.27)Ti(1.73))O(4), but is also applicable to other layered titania and other non-titanium-based layered metal oxides. Therefore, it was clarified that AEP reactions are widely applicable routes to prepare various compounds, including those that are difficult to synthesize by other reactions.     

Three types of reactions with intramolecular five-membered ring compounds in organic synthesis

There are three types of reactions with intramolecular five-membered ring compounds in organic syntheses: The first type is reactions involving intramolecular five-membered ring compounds which are utilized for the ease of synthesis of these compounds and the stability of the products. The second is reactions performed via intramolecular five-membered ring intermediates, because such intermediates are very reactive and labile compounds. The third is the metal-catalyzed reactions with the intramolecular five-membered ring compounds because these metal compounds have catalytic activities. The third type reactions involving intramolecular five-membered ring pincer compounds are also provided.The first type reactions include carbonylations, alkenylations, alkynylations, acylations, isocyanations, Diels-Alder reactions, etc. The second type reactions include carbonylations, cross-coupling reactions, hydroacylations, ring expansion reactions, carbocyclizations, etc. The third type reactions include cross-coupling reactions, rearrangements, metatheses, reductions, Michael reactions, dehydrogenations, Diels-Alder reactions, etc.     

Reaktionen von Tetraphosphortrisulfid mit Kupferhalogeniden

Reactions of Tetraphosphorus Trisulfide with Copper Halides The reactions of tetraphosphorus trisulfide with copper halides have been studied. From these reactions the compounds P₄S₃CuX (X = Cl, Br, I) were isolated. Their infrared spectra are discussed. The properties of the compounds suggest a polymeric structure. The behaviour of the tetraphosphorus trisulfide is compared with those of the phosphines.     

Reactions between or within molecular crystals

Reactions that occur within or between molecular crystals, in particular those reactions that are activated by mechanical methods, are reviewed. The focus is on processes (whether intrasolid or intersolid) that are controlled primarily by supramolecular bonding, such as template cycloadditions, formation of inclusion compounds, reactions between molecular crystals by the reassembling of noncovalent bonds, and the formation of complexes and coordination compounds. It is proposed that solvent-free mechanochemical methods, for example, cogrinding, milling, and kneading, represent viable "green" routes for the preparation of novel molecular and supramolecular solids.     

Sterically crowded aryloxide compounds of aluminum

The chemistry of aluminum compounds containing sterically demanding aryloxide ligands is presented. In particular, those of compounds derived from 2,6-di-tert-butyl-4-methylphenol (BHT-H, from the trivial name butylated hydroxytoluene). The synthesis and structure of three-coordinate monomeric derivatives, and their ligand exchange reactions, are discussed in comparison to the more typical four-coordinate oligomeric aluminum alkoxide and aryloxide compounds. The reactions of the sterically crowded aryloxide compounds is divided into four general classes: oxidation and hydrolysis, the formation of Lewis acid-base complexes, the reaction with organic carbonyls, and the reaction with main group halides. Alane-aryloxide compounds are discussed separately, as are the 1,3-diphenyltriazenide derivatives. Finally, a discussion of the Al---O bonding interactions in four-coordinate aluminum aryloxides is presented, giving spectroscopic and theoretical evidence for and against various postulates to explain the presence of short Al-O distances and large Al---O---C angles.