Carbon-carbon Multiple Bonds Research Articles

Chemical Reactivity of Alkenes and Alkynes As Seen from Activation Energies, Enthalpies of Protonation, and Carbon 1s Ionization Energies

Electrophilic addition to multiple carbon-carbon bonds has been investigated for a series of twelve aliphatic and aromatic alkenes and the corresponding alkynes. For all molecules, enthalpies of protonation and activation energies for HCl addition across the multiple bonds have been calculated. Considering the protonation process as a cationic limiting case of electrophilic addition, the sets of protonation enthalpies and gas-phase activation energies allow for direct comparison between double- and triple-bond reactivities in both ionic and dipolar electrophilic reactions. The results from these model reactions show that the alkenes have similar or slightly lower enthalpies of protonation, but have consistently lower activation energies than do the alkynes. These findings are compared with results from high resolution carbon 1s photoelectron spectra measured in the gas phase, where the contribution from carbons of the unsaturated bonds are identified. Linear correlations are found for both protonation and activation energies as functions of carbon 1s energies. However, there are deviations from the lines that reflect differences between the three processes. Finally, substituent effects for alkenes and alkynes are compared using both activation and carbon 1s ionization energies.

Photoinduced Addition Reactions in Aqueous Media

The scope of this account on addition reactions in aqueous media is to demonstrate that the syntheses of useful targets or functionalizations can be accomplished through photoaddition reactions in benign environments. Ammination reactions of olefins and constrained cycloalkanes, addition products derived from quinonemethides, aromatic arylation reactions of furanones and alkenes, and radical addition reactions to α,β-unsaturated aldehydes performed in aqueous media constitute valuable reactions and hence interesting synthetic targets in organic syntheses. In studying these synthetic targets, different light sources are employed to achieve excitation. Also, photoinduced electron transfer sequences will account for the addition products. This account does exclude the photoaddition reactions performed by the aid of metals or metallic complexes, or the addition of perfluoroalkyl radicals to carbon-carbon and carbon-heteroatom multiple bonds in aqueous media. Keywords: Photoaddition in aqueous media, Photoinduced electron transfer addition in aqueous media, Radical additions in aqueous media, carbon-carbon multiple bonds, 4-amino-1, 2-benzocycloheptene (2d), Rehm-Weller equation, 2-methyl-1, 4-benzoquinone, ketonization, fluorescence, UV_vis spectroscopy

ChemInform Abstract: Copper‐Catalyzed Highly Selective Semihydrogenation of Non‐Polar Carbon—Carbon Multiple Bonds Using a Silane and an Alcohol.

AbstractThe optimized conditions are applied to a wide range of internal and terminal alkynes to provide the products with complete (Z)‐selectivity.

Synthesis of Carboxylic Acids and Derivatives Using CO2 as Carboxylative Reagent

The catalytic transformation of carbon dioxide into high value-added fine chemicals has attracted attention because this will make CO 2 into an abundant, inexpensive, and renewable C 1 feedstock. More than 20 reactions involving CO 2 as a starting material have been developed in recent decades but their successful industrialization is limited. One type of reactions that is technologically viable is to use CO 2 as a carboxylative reagent in the production of a wide range of carboxylic acids and derivatives. This review focused on transition metal-catalyzed reactions for the synthesis of various carboxylic acid and derivatives from CO 2 , by the carboxylation of carbon nucleophiles and C-H bonds and reactions of CO 2 with unsaturated organic compounds (especially those with a carbon-carbon multiple bond). This review also included transition metal-free or organocatalytic reactions for the transformation of CO 2 into carboxylic acid and derivatives. 二氧化碳是储量丰富、廉价易得且可再生的 C 1 资源, 将其催化转化成高附加值精细化学品的研究已经引起了人们的广泛关注. 目前, 虽然二氧化碳用作初始原料的反应已经工业化的很少, 但过去几十年中仍有二十多个具有实际应用前景的二氧化碳参与的新反应被发现, 其中以二氧化碳作为羧化试剂合成各种羧酸及其衍生物的反应为突出代表. 本文综述了过渡金属催化合成羧酸及其衍生物的二氧化碳与多种碳亲核试剂、碳氢键以及碳碳多重键化合物的反应, 并总结了无过渡金属参与或有机小分子催化条件下将二氧化碳转化成羧酸及其衍生物的反应. This review summarized transition metal-catalyzed reactions of CO 2 with carbon nucleophiles, C-H bond and unsaturated organic compounds for the synthesis of carboxylic acid and derivatives using CO 2 as a carboxylative reagent.

Aryl Aldehydes as Traceless Dielectrophiles in Bifunctional Titanocene-Catalyzed Propargylic C–X Activations

The titanocene-catalyzed construction of all-carbon substituted tertiary centers directly from aromatic aldehydes is described. The starting aldehyde behaves as a traceless functionality in the formation of multiple carbon-carbon bonds through consecutive carbon-heteroatom bond activations. The sequential addition of a metal acetylide and a second carbon nucleophile to the dielectrophilic aldehyde enables the construction of symmetrical and unsymmetrical 1,4-diynes in good yields.

Recent Progress in Transition Metal Complexes Catalyzed Hydrosilylation of Carbon-Carbon Multiple Bonds

Recent progress in the catalytic hydrosilylation of organic compounds containing carbon-carbon multiple bonds is reviewed. Hydrosilylation of carbon-carbon multiple bonds catalyzed with transition metal complexes remains the most commercially utilized process for formation of organosilicon compounds. During the last two decades, a number of simple and versatile catalytic systems including homogenous and heterogenous systems and even those for asymmetric catalysis procedures have been developed. These transition metal catalysts increased catalytic efficiency as well as regioselectivity and stereoselectivity. Keywords: Hydrosilylation, catalysis, carbon-carbon multiple bonds, transition metal complexes, Silicon, phosphonic acids, bisphosphonic acids, organosilicon-mediated synthesis, phosphites, regioselective hydrosilylation, Palladium Complexes, chiral phosphines, asymmemetric hydrosilylation, Nickel Complexes, Cobalt Complexes

Thirty Six Years of Research on the Selective Reduction and Hydroboration

From 1975 to 2011, for thirty six years, the author and his collaborators have developed a variety of reducing and hydroborating agents, and applied them to organic synthesis, which involves the 1,2-reduction of <TEX>${\alpha}$</TEX>,<TEX>${\beta}$</TEX>-unsaturated carbonyl compounds, stereoselective reduction of cycloalkanones, regioselective ring-opening of epoxides, partial reduction of carboxylic acid derivatives to aldehydes, regioselective addition to carbon-carbon multiple bonds, etc. by utilizing metal hydrides and the newly-devised the Meerwein-Ponndorf-Verley (MPV) type reagents. Such developments provide a new synthetic methodology making possible valuable selective reductions and hydroborations, not practical previously.

Palladium nanoparticle-cored G 1-dendrimer stabilized by carbon–Pd bonds: synthesis, characterization and use as chemoselective, room temperature hydrogenation catalyst

Palladium nanoparticle-cored Fréchet type G 1-dendrimer ( Pd-G 1 ) stabilized by Pd–carbon bonds is synthesized and characterized by IR, NMR, UV–Vis and TEM. Pd-G 1 was found to be a highly efficient, chemoselective and reusable catalyst for the room temperature hydrogenation of carbon–carbon multiple bonds. Reducible functionalities like CHO, CO, COOR, CN, NO 2 and halogens were unaffected. Pd-G 1 is projected as an efficient catalyst for the selective hydrogenation of carbon-carbon multiple bonds in multifunctional organic molecules.

ChemInform Abstract: Use of the Simple and Extended Grunwald—Winstein Equations in the Correlation of the Rates of Solvolysis of Highly Hindered Tertiary Alkyl Derivatives

AbstractReview: 48 refs.

Reactions of aldoketeniminophosphonates with CH-acids

Aiming to obtain new polyfunctional organophosphorus compounds, we studied the reactions of aldoketeniminophosphonates with different CH-acids. The reactions were shown to proceed efficiently in anhydrous acetonitrile medium in the presence of the catalytic amounts of potassium carbonate to form the products of the addition of CH-acids to a multiple carbon-carbon bond followed by the prototropic isomerization to the corresponding γ-substituted β-functional alkylaminoethenephosphonates. The reaction of aldoketeniminophosphonates with CH-acids is found to depend significantly on the strength and nature of the acid. The formation of the carbon-carbon bond is possible mainly in the case of the CH-acids whose pKa values lie within 10–14.

Asymmetric additions to dienes catalysed by a dithiophosphoric acid

Chiral Brønsted acids have become an invaluable tool for achieving a variety of asymmetric chemical transformations under catalytic conditions while avoiding the use of toxic and expensive metals1–8. While the catalysts developed so far are remarkably effective at activating polarized functional groups, chemists have not yet been able to use organic Brønsted acids to catalyze highly enantioselective transformations of unactivated carbon-carbon multiple bonds. This deficiency persists despite the fact that racemic acid-catalyzed “Markovnikov” additions to olefins are a well-established part of the chemist’s toolbox. Here we show that chiral dithiophosphoric acids catalyze the intramolecular hydroamination and hydroarylation of dienes and allenes to generate heterocyclic products in exceptional yield and enantiomeric excess. To help rationalize the unique success of this catalytic system, we present a mechanistic hypothesis that involves the addition of the acid catalyst to the diene followed by SN2′ displacement of the resulting dithiophosphate intermediate. Mass spectrometry and deuterium labelling studies are presented in support of the proposed mechanism. The catalysts and concepts revealed in this study should prove applicable to other asymmetric functionalizations of unsaturated systems.

Samarium diiodide induced ketyl-(het)arene cyclisations towards novel N-heterocycles

In this tutorial review we discuss recent advances in the field of ketyl-(het)arene cyclisations promoted by samarium diiodide and related processes. Couplings of samarium ketyls with carbon-carbon multiple bonds are perhaps the most useful reactions to create carbocycles and heterocycles of various ring sizes. They have also successfully been exploited for the synthesis of biologically active compounds or natural products. In this article we intend to summarise our diversity orientated approaches towards nitrogen heterocycles and emphasize other approaches with SmI(2) as well as electrochemical cyclisation methods providing similar N-heterocycles. We also briefly discuss our recently published formal total synthesis of strychnine employing a new samarium diiodide induced cascade reaction as key step. All these examples demonstrate the high synthetic potential of samarium ketyl-(het)arene cyclisations for the preparation of various types of important heterocyclic compounds.

Intramolecular OH⋯π interactions in alkenols and alkynols

The vibrational overtone spectra of propargyl alcohol (prop-2-yn-1-ol, PA), allyl alcohol (prop-2-en-1-ol, AA), propargyl carbinol (but-3-yn-1-ol, PC) and allyl carbinol (but-3-en-1-ol, AC) were recorded with intracavity laser photoacoustic spectroscopy (ICL-PAS) in the Δv(OH) = 3, 4 and 5 regions for propargyl alcohol and allyl alcohol and in the Δv(OH) = 4 and 5 regions for propargyl carbinol and allyl carbinol. Local mode anharmonic oscillator calculations were performed with explicitly correlated coupled cluster methods to guide spectral assignment. Atoms in molecules (AIM) and non-covalent interactions (NCI) calculations were carried out to analyze the interactions between the OH-group and the π-electrons of the carbon-carbon multiple bonds. We ascertain the effect of the carbon chain length and saturation on the conformation and spectroscopy of the four alcohols in relation to intramolecular hydrogen bonding interactions.

遷移金属錯体によるカルボニル官能基のアルキンへの付加反応

Transition-metal-catalyzed transformation to produce various kinds of carbonyl compounds is one of the most powerful synthetic methods. Among them, transition-metal-catalyzed addition reactions of carbonyl compounds to carbon-carbon multiple bonds such as alkynes are environmentally friendly because all atoms of the substrates are retained in the products. Although the addition of aldehydes to alkynes, hydroacylation, has been intensively studied, the addition of acid chlorides, formamides, and formates has not been fully developed. One plausible explanation for it is the occurrence of competing decarbonylation reactions. In addition, relatively lower reactivity of formamides or formates limits the application as substrates in these addition reactions. In this paper, we overview recent results on the transition-metal-catalyzed addition reactions of carbonyl functionalities to alkynes.

ChemInform Abstract: From Vinylogation to Alkynylogation: Extending the Reactivity of Enolates

AbstractReview: 57 refs.

Chiral Cationic Platinum Complexes: New Catalysts for The Activation of Carbon-Carbon Multiple Bonds Towards Nucleophilic Enantioselective Attack

The concept of π-acid catalysis has emerged as a powerful principle for the chemists to create diversity and originality from simple molecules. Carbophilic late transition metals such as gold or platinum have appeared as fascinating catalysts able to activate alkenes, alkynes and other unsaturated derivatives towards anti nucleophilic addition via complexation on a single empty coordination site. Tunable chiral square-planar cationic platinum complexes created by combination of a mono- and a bidentate ligand appear as a new class of highly promising asymmetric catalytic systems. This highlight intends to stress the potential applications in enantioselective catalytic reactions associated with a variety of chiral cationic tricoordinated platinum complexes recently described in the literature. Keywords: alkene, alkyne, asymmetric catalysis, cationic and carbophilic complexes, cycloisomerization reaction, enyne, Lewis acid, platinum

ChemInform Abstract: Novel Aromatic Tetracarboxylic Acid Dianhydrides.

The Diels-Alder reactions of 4,4′-bis(2,4,5-triphenylcyclopentadienon-3-yl)benzophenone with carboxylic anhydrides containing multiple carbon-carbon bonds afforded novel tetracarboxylic dianhydrides.

Use of the Simple and Extended Grunwald-Winstein Equations in the Correlation of the Rates of Solvolysis of Highly Hindered Tertiary Alkyl Derivatives

The original Grunwald-Winstein equation (1948) involved the development of a scale of solvent ionizing power (Y). Subsequent work has refined this scale and involved the development of scales of solvent nucleophilicity (N) and a term to correct for deviations when aromatic rings are present, governed by the aromatic ring parameter (I). These three scales, and the sensitivities towards each, can be related to specific rates of solvolysis through linear free energy relationships (LFERs).One important area of application of LFERs has been to the solvolyses of tert-alkyl halides. It has been proposed that the solvolysis of tert-butyl chloride involves a nucleophilic component, although other workers have suggested that the effects observed are related to electrophilic not nucleophilic influences. Takeuchi (1997) studied a compound with two of the methyl groups of tert-butyl chloride replaced by neopentyl groups. For this highly-hindered substrate there was no evidence for nucleophilic participation. Liu (1998) and Takeuchi (2001) have reported concerning the solvolyses of additional significantly-hindered tertiary alkyl chlorides. Liu (2009) has presented a parallel study of bromides. Martins (2008) has considered hindered tertiary alkyl halides, mainly with carbon-carbon multiple bonds as substituents. It was proposed that the hI term was of importance, with the sensitivities (h) sometimes positive and sometimes negative. To explain negative values, it was suggested that the I scale might contain a nucleophilicity component. In this review, we bring together, with analysis and commentary, the work of Takeuchi, Liu, Martins and others concerning the solvolyses of tertiary alkyl halides, with emphasis on the relevance of the three scales that have been developed for use in Grunwald-Winstein correlations.

From Vinylogation to Alkynylogation: Extending the Reactivity of Enolates

Extending reactivity through conjugated multiple carbon-carbon bonds can be a rapid way to expand the scope of synthetic chemistry. In this account, we describe our research on the alkynylogation of enolates. We conducted a systematic investigation on reactions of alkynyl- and allenyl-substituted enolates with various electrophiles. Those reactions led to the convenient synthesis of highly functionalized allenes, alkynes, and 1,3-dienes. Some relevant literature reports are also described.

Two Distinct Mechanisms of Alkyne Insertion into the Metal–Sulfur Bond: Combined Experimental and Theoretical Study and Application in Catalysis

The present study reports the evidence for the multiple carbon-carbon bond insertion into the metal-heteroatom bond via a five-coordinate metal complex. Detailed analysis of the model catalytic reaction of the carbon-sulfur (C-S) bond formation unveiled the mechanism of metal-mediated alkyne insertion: a new pathway of C-S bond formation without preliminary ligand dissociation was revealed based on experimental and theoretical investigations. According to this pathway alkyne insertion into the metal-sulfur bond led to the formation of intermediate metal complex capable of direct C-S reductive elimination. In contrast, an intermediate metal complex formed through alkyne insertion through the traditional pathway involving preliminary ligand dissociation suffered from "improper" geometry configuration, which may block the whole catalytic cycle. A new catalytic system was developed to solve the problem of stereoselective S-S bond addition to internal alkynes and a cost-efficient Ni-catalyzed synthetic procedure is reported to furnish formation of target vinyl sulfides with high yields (up to 99%) and excellent Z/E selectivity (>99:1).