Reactions of the Carbonyl Group in Fluorinated Ketones

The chemistry of polyfluorinated ketones has recently received a great deal of attention.

1 A. Ya. Yakoubovich, Usp. Chim. 25, 3 (1956).

2 H. P. Braendlin and E. T. McBee in: Advances in Fluorine Chemistry. Butterworths, London 1963, Vol. 3, p. 1.

3 The review by Braendlin and McBee [2] does not deal only with perfluorinated ketones; moreover, though published in 1963, it is already outdated. The papers discussed in [1,2] will not be reviewed in the present article.

. The carbonyl and imino groups of the fluorinated ketones and their imines react in many different ways. In particular, the electron-attracting perfluoroalkyl groups intensify the electrophilic properties and weaken the nucleophilic properties of the carbonyl group. The perfluoroalkyl group also hinders the heterolytic removal of the hydroxyl group from adducts by reducing the stability of the carbonium ion . The increased electrophilicity of the carbonyl group and the increased stability of the addition products leads not only to a change in reactivity in the characteristic ketone reactions, but also to numerous new reactions which are not observed with non-fluorinated ketones. Thus it is possible to synthesize a wide variety of fluoroorganic compounds from perfluorinated ketones.

4 We have been concerned mainly with hexafluoroacetone, since in addition to being the most readily available and simplest perfluorinated ketone, this is also a typical representative of this class of compounds.

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N-Acetyl-N,N-dipyrid-2-yl (cyclooctadiene) rhodium (I) and iridium (I) complexes: Synthesis, X-ray structures, their use in hydroformylation and carbonyl hydrosilylation reactions and in the polymerization of diazocompounds

The synthesis of novel N-acetyl-N,N-dipyrid-2-yl complexes of Rh^I and Ir^I, i.e. [RhCl(CH₃CONPy₂)(COD)] (1) and [IrCl(CH₃CONPy₂)(COD)] (2), respectively, is described. Upon prolonged treatment in CH₂Cl₂ at room temperature, complex 1 is transformed into a cationic Rh-complex, i.e. [Rh(CH₃CONPy₂)(COD)⁺RhCl₂(COD)⁻] (1a). Compound 1a crystallizes in the monoclinic space group P2₁/c, complex 2 crystallizes in the triclinic space group . Compound 1 was investigated for its catalytic activity in the hydroformylation of cyclooctene as well as of 1-octene. In addition, 1 was used in various carbonyl hydrosilylation reactions of both aldehydes and ketones. There, turn-over numbers up to 50 000 and yields in the range of 85-100% were observed. Finally, compound 1 was successfully used for the polymerization of N₂CHCOOEt yielding highly stereoregular poly(ethoxycarbonylcarbene) with M_w = 67 000 g/mol and a polydispersity index (PDI) of 2.59.     

Generation and Trapping Reactions of a Formal 1:1 Complex between Singlet Carbon and 2,2′-Bipyridine

The structural element of a protonated imidazolium system was realized for the first time in the synthesis of 1 from 2,2′-bipyridine and a novel methylenating agent. Reversible deprotonations proceed via 2 to lead to carbene 3 , a formal 1:1 complex between singlet carbon and 2,2′-bipyridine which is stable in solution and can be trapped. For 1 and 2 , unusual hybridizations of the bridging C atom were found experimentally.     

Reactions of Enaminones with Diazocarbonyl Compounds

The [Cu(acac)₂]‐catalyzed reactions of several tertiary enaminones with three diazocarbonyl compounds, i.e., dimethyl diazomalonate, ethyl diazoacetoacetate, and ethyl diazoacetate, yielded amino‐ and additionally carbonyl‐substituted dihydrofurans, together with further furan derivatives. Due to the conjugation of α‐carbonyl/α‐Ph groups, reactions proceeded only via 1,5‐electrocyclization of corresponding keto‐ylides. On the other hand, in the absence of any α‐substituent, tertiary enaminone and ethyl diazoacetate, reacted via an accompanying mechanism by a push‐pull cyclopropane intermediate, to yield a 2,4‐dicarbonyl‐substituted furan in one step with moderate yield.     

二卤卡宾与羰基化合物反应的研究进展

对近年来二卤卡宾与羰基化合物的反应机理研究进行了总结，指出二卤羰基Ｙｉｌｄｅ为反应的中间体，并对影响二卤羰基Ｙｌｉｄｅ的稳定性及后续反应的因素如底物的立体效应，取代基的电子效应，Ｃａｐｔｏｄａｔｉｖｅ效应以卤原子半径大小进行了讨论。     

硒催化反应最新研究进展

价廉易得的非金属硒作催化剂不但具有良好的催化活化CO的性能及反应过程相转移催化特性, 而且能循环使用. 用Se/CO催化体系替代贵金属催化羰基化法及剧毒的光气法进行羰基化反应及用Se/CO/H2O催化体系进行高选择性的还原反应, 具有反应条件温和、原子经济性高、成本低、环境友好、路线简短、后处理方便等优点, 因而引起人们的广泛关注. 概述了近几年来硒催化羰基化反应和硒催化选择性还原反应的最新研究进展, 并对硒催化反应的发展趋势进行了展望.     

Ligand Effects on the Chemoselectivity of Transition Metal Catalyzed Reactions of α-Diazo Carbonyl Compounds

The transition metal catalyzed reaction of α-diazo carbonyl compounds has found numerous applications in organic synthesis, and its use in either heterocyclic or carbocyclic ring formation is well precedented. Early work in this area made use of insoluble copper catalysts. Although these catalysts are still employed today, their use has decreased significantly with the advent of homogeneous copper catalysts and catalysts based on other metals. The discovery that Rh^II carboxylates facilitate nitrogen loss from diazo compounds rekindled significant interest in the field of diazo/carbenoid chemistry. Since the realization that Rh^II carboxylates are superior catalysts for the generation of transient electrophilic metal carbenoids from α-diazo carbonyl compounds, intramolecular carbenoid addition and insertion reactions have assumed strategic importance in C? C bond-forming reactions in organic synthesis. In contrast to other catalysts that are suitable for carbenoid reactions of diazo compounds, those constructed with the dirhodium(II ) framework are most amenable to ligand modifications that, in turn, can influence reaction selectivity. This article will emphasize the chemical behavior of transition metal carbenoid complexes that are greatly affected by the nature of the ligand groups attached to the metal center. Much of the discussion will center on the ability of the dirhodium(II ) ligands to determine reaction preference toward different functional groups on the same molecule.     

Organic Polyvalent Iodinc Reagents-Promoted Coupling Reaction of 1-Alkynes

Sincetheearlyl980sinterestin0rganicpoIyvalentiodinec0mp0undshasexperiencedaresurgence'.Afewexamplesofhomo-couplingreacti0nsviathesec0mpoundshavebeenrep0rted-.Wef0undthatl-aIkyneswereeasytoc0upleinthepresenceofPhI(OAc)=orPhI(OH)OTs,catalyticCulandbase,t0aff0rdc0njugateddiynes.l,3-Diyneplaysanimportantr0leinstudiesofm0lecularrec0ngnition',innaturalpr0ducts',andinsynthesis.AlthoughEglintonreaction',Cadi0t-Chalkiewiczc0upling'andGlaserreaction5haveprovidedc0nvenientmeth0dst0synthesizeconjug…     

金催化去芳构化反应研究进展

均相金催化在过去十几年经历了飞速的发展,展现出了非常高的催化效率和非常强的官能团兼容性.另一方面,催化去芳构化反应能够直接高效地将芳香化合物转化为高度官能团化的具有丰富三维立体结构的分子.因此,金催化去芳构化反应将会为天然产物和复杂分子的合成提供新颖直接高效的路径.本文总结了近几年金催化去芳构化反应的例子,主要可分为金催化的重排反应和炔烃/联烯的氢-官能团化反应两方面,同时还介绍了这两类反应的特点与可能的反应机理.     

铜催化交叉偶联反应研究的新进展

对Cu催化交叉偶联反应的最新研究进展作了综述 .该反应涉及碳—碳、碳—氮、碳—氧、碳—硫、碳—硒、以及碳—卤的成键 .反应的类型包括Ullmann反应、Suzuki反应、Stille反应以及Heck反应等 .还详细地介绍了Cu催化交叉偶联反应中选用不同的铜盐、配体以及溶剂时所产生的效果     

Reactions of Thioketones Possessing a Conjugated CC Bond with Diazo Compounds

The reactions of several thioketones containing a conjugated C?C bond with diazo compounds were investigated. All of the selected compounds reacted via a 1,3‐dipolar cycloaddition with the C?S group and subsequent N₂ elimination to yield thiocarbonyl ylides as intermediates, which underwent a 1,3‐dipolar electrocyclization to give the corresponding thiirane 25 , or, by a subsequent desulfurization, to give the olefins 33a and 33b . None of the intermediate thiocarbonyl ylides reacted via 1,5‐dipolar electrocyclization. If the α,β‐unsaturated thiocarbonyl compound bears an amino group in the β‐position, the reactions with diazo compounds led to the 2,5‐dihydrothiophenes 40a – 40d . In these cases, the proposed mechanism of the reactions led once more to the thiocarbonyl ylides 36 and thiiranes 38 , respectively. The thiiranes reacted via an S_Ni′‐like mechanism to give the corresponding thiolate/ammonium zwitterion 39 , which underwent a ring closure to yield the 2,5‐dihydrothiophenes 40 . Also in these cases, no 1,5‐dipolar electrocyclization could be observed. The structures of several key products were established by X‐ray crystallography.     

RP-Bridged Metal Carbonyl Clusters: Synthesis,Properties, and Reactions

Metal carbonyl clusters possess a complicated chemistry that is only beginning to be understood. One of the main current goals in this area is thus an understanding of their reactivity. This article describes the syntheses and reactions of clusters that contain metal carbonyl fragments bridged by a main-group element. But what is the sense of making such clusters still more complicated by the incorporation of main-group elements? The example of μ₃-bridged carbonyl clusters will serve to show that the main-group element plays an important role in the study of reaction paths; it holds the metal carbonyl fragments together even when the bonds between them are broken in the course of a reaction. Trinuclear μ₃-bridged clusters prove to be small enough to allow the analysis of typical cluster reactions (such as the reversible breaking of metal-metal bonds) in terms of single reaction steps. They are also large enough to provide surprises by their multifaceted reactivity. It will be shown that a detailed study of trinuclear RX-bridged metal carbonyl clusters (X ? N, P, As, Sb, Bi)—a very small part of carbonyl cluster chemistry—can lead to a better understanding of the general reaction principles involved.     

A Convenient,Selective Synthesis of Bis[2,4‐bis(trifluoromethyl)phenyl]phosphane Derivatives Starting from 1,3‐Bis(trifluoromethyl)benzene

The reaction of the sterically shielded phosphane derivative, dichlorodiethylaminophosphane, Cl₂PNEt₂, with an excess of a mixture of 2,6‐bis(trifluoromethyl) and 2,4‐bis(trifluoromethyl)phenyl lithium gives bis[2,4‐bis(trifluoromethyl)phenyl]diethylaminophosphane, [2,4‐(CF₃)₂C₆H₃]₂PNEt₂, in 72 % yield as a colourless solid, while 2,6‐bis(trifluoromethyl)phenyl lithium remains unchanged in solution. The amino derivative crystallizes in the monoclinic space group P2₁/c (a 869.2(1), b 1857.4(1), c 1357.6(1) pm, β 100.57(4)°, Z = 4). Treatment of [2,4‐(CF₃)₂C₆H₃]₂PNEt₂ in CHCl₃ solution with conc. HCl allows the synthesis of [2,4‐(CF₃)₂C₆H₃)]₂PCl. [2,4‐(CF₃)₂C₆H₃]₂PCl reacts with H₂O in THF solution with quantitative formation of the corresponding secondary phosphane oxide. To obtain bis[2,4‐bis(trifluoromethyl)phenyl]phosphinic acid, [2,4‐(CF₃)₂C₆H₃]₂P(O)OH, quantitatively, a CHCl₃ solution of [2,4‐(CF₃)₂C₆H₃]₂P(O)H, has to be stirred in an NO₂ atmosphere. The phosphinic acid crystallizes is the triclinic space group (a 754.2(1), b 927.6(2), c 1305.5(2) pm, α 85.11(2)°, β 75.45(1)°, γ 79.99(2)°, Z = 2). From the reaction of the phosphinic acid with either elemental sodium or with cyanide salts, the corresponding phosphinate salts are obtained in an almost quantitatively yield.     

Observations on the copper(II) catalyzed reactions of enaminones and dimethyl diazomalonate

The Cu(acac)₂ catalyzed reactions of dimethyl diazomalonate with enaminones yielded 1,5-cyclization and α-CH insertion products. In the case of anilino derivatives (R¹ or R² = Ph), products resulting from an unusual insertion to the benzoyl ring dominated the reaction.     

New Methods of Preparative Organic Chemistry. Transfer of Diazo Groups

When an arenesulfonyl azide, particularly p-toluenesulfonyl azide, reacts, in the presence of a base, with a compound containing an active methylene group, the two hydrogen atoms of the active methylene group are replaced by a diazo group to form a diazo compound and an arenesulfonamide. The method may be used for the synthesis of the diazo derivatives of cyclopentadienes, cyclohexadienes, 1,3-dicarbonyl, 1,3-disulfonyl, and 1,3-ketosulfonyl compounds, ketones, carbonic acid esters, and β-iminoketones. Secondary reactions can lead to azo compounds and heterocycles such as 1,2,3-triazoles, 1,2,3-thiadiazoles, and pyrazolin-4-ones. Azidinium salts react in the same way, but in this case an acidic reaction medium is necessary, a fact that is sometimes advantageous.     

Reactions of (1E)‐Buta‐1,3‐dien‐1‐yl Acetate with Diazocarbonyl Compounds

Carbene transfer to appropriate substrates is a highly versatile tool for the construction of carbon frameworks with increased functional and structural complexity. In this study, some novel cyclopropane derivatives were synthesized via carbenoid reactions and their further reactivities were investigated. (1E)‐Buta‐1,3‐dien‐1‐yl acetate was reacted with four different diazocarbonyl compounds, ethyl diazoacetate, dimethyl diazomalonate, 1‐diazo‐1‐phenylpropan‐2‐one, and methyl (3E)‐2‐diazo‐4‐phenylbut‐3‐enoate, in the presence of two catalysts. All synthesized substituted cyclopropanes were obtained chemoselectively with respect to less‐hindered C?C bonds. Under the applied conditions, while cyclopropanes 7a and 7d underwent further reactions, cyclopropanes 7b and 7c were stable enough. Cyclopropanes 7a and an additional equivalent of ethyl diazoacetate yielded polyfunctionalized cyclohexenes. Cyclopropanes from methyl (3E)‐2‐diazo‐4‐phenylbut‐3‐enoate yielded polyfunctionalyzed cycloheptadiene isomers by Cope rearrangement.     

铜催化C-N交叉偶联反应的研究进展

对铜催化的C-N交叉偶联反应的最新研究进展作了综述.按照反应中含氮化合物种类的不同将亲核试剂分为氨基酸、胺、酰胺、含氮芳香杂环化合物、其它含氮化合物五类,对各类亲核试剂参与反应的体系(包括亲电试剂、催化剂前驱体、配体、溶剂、温度、碱、反应时间)做了全面归纳,在此基础上以配体为主线对各类亲核试剂涉及的反应进一步做了详细介绍.另外,对这一反应的机理研究也做了综述.     

苯炔参与的去芳构化反应研究进展

去芳构化反应是有机化学热点研究领域之一,可从二维平面分子出发构筑高官能团化的三维立体分子.近年来,苯炔作为一类高活性中间体被有机化学家们广泛用于去芳构化反应研究中,并取得了一系列创新成果.从含氮芳杂环同苯炔的去芳构化反应、苯炔与双烯体的[4+2]环加成去芳构化反应以及苯炔以其它途径参与的去芳构化反应三个方面,对机理进行...     

铜催化C—S偶联反应的研究新进展

铜催化C—S偶联反应是有机合成中的重要手段,近年来一直是有机化学和催化化学的研究热点之一.按照反应中所使用的配体的不同对铜催化C—S偶联反应的研究新进展进行了综述.