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1.
Insertion of CO2 into a palladium allyl bond and a Pd(II) catalysed carboxylation of allyl stannanes
The complex 2,6-bis[(di-t-butylphosphino)methyl]phenyl allyl palladium (PCP(tBu)Pd-allyl, 3) reacts with CO(2) in a very fast insertion reaction to give the corresponding butenoate complex. The reaction is thought to occur via a cyclic six-membered transition state (7), where the gamma-carbon of the allyl group is linked up with the CO(2)-carbon. A group of related PCP complexes were investigated as catalysts for the carboxylation of tributyl(allyl)stannane. A catalytic cycle is proposed for this reaction where the rate determining step is the transmetallation between tin and palladium. The carboxylation reaction is faster using less sterically crowded catalysts whereas the electron richness of the palladium complexes seems less important for reactivity. Thus, there was no apparent difference in reactivity between 2,6-bis[(di-phenylphosphino)methyl]phenyl palladium triflouroacetate (13) and resorcinolbis(diphenyl)phosphinite palladium triflouroacetate (10). Both of these complexes give high turnovers for the carboxylation of tributyl(allyl)stannane (80% in 16 h using a ca. 5% catalyst loading and 4 atm CO(2) pressure). On the other hand complex 3 was inactive in the catalytic carboxylation reaction. 相似文献
2.
Dr. Masanori Takimoto Sandeep Suryabhan Gholap Prof. Dr. Zhaomin Hou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(35):8363-8370
The alkylative carboxylation of ynamides and allenamides with CO2 and alkylzinc halides catalyzed by a copper catalyst was developed. A variety of alkylzinc halides bearing functional groups were used for this transformation to afford α,β-unsaturated carboxylic acids, which contain the α,β-dehydroamino acid skeleton, introducing the corresponding alkyl group and CO2 across the carbon–carbon triple or double bond. This alkylative carboxylation formally consists of Cu-catalyzed carbozincation of ynamides or allenamides with alkylzinc halides and the subsequent nucleophilic carboxylation of the resulting alkenylzinc species with CO2. This protocol would be a useful method for the synthesis of α,β-dehydroamino acid derivatives possessing a functionalized alkyl group due to the high regio- and stereoselectivity, simple one-pot procedure as well as the use of CO2 as a starting material. 相似文献
3.
Dr. Toni Moragas Dr. Morgane Gaydou Prof. Ruben Martin 《Angewandte Chemie (International ed. in English)》2016,55(16):5053-5057
A user‐friendly Ni‐catalyzed reductive carboxylation of benzylic C?N bonds with CO2 is described. This procedure outperforms state‐of‐the‐art techniques for the carboxylation of benzyl electrophiles by avoiding commonly observed parasitic pathways, such as homodimerization or β‐hydride elimination, thus leading to new knowledge in cross‐electrophile reactions. 相似文献
4.
Lu CT Chen SA Bretaña NA Cheng TH Lee TY 《Journal of computer-aided molecular design》2011,25(10):987-995
In proteins, glutamate (Glu) residues are transformed into γ-carboxyglutamate (Gla) residues in a process called carboxylation.
The process of protein carboxylation catalyzed by γ-glutamyl carboxylase is deemed to be important due to its involvement
in biological processes such as blood clotting cascade and bone growth. There is an increasing interest within the scientific
community to identify protein carboxylation sites. However, experimental identification of carboxylation sites via mass spectrometry-based
methods is observed to be expensive, time-consuming, and labor-intensive. Thus, we were motivated to design a computational
method for identifying protein carboxylation sites. This work aims to investigate the protein carboxylation by considering
the composition of amino acids that surround modification sites. With the implication of a modified residue prefers to be
accessible on the surface of a protein, the solvent-accessible surface area (ASA) around carboxylation sites is also investigated.
Radial basis function network is then employed to build a predictive model using various features for identifying carboxylation
sites. Based on a five-fold cross-validation evaluation, a predictive model trained using the combined features of amino acid
sequence (AA20D), amino acid composition, and ASA, yields the highest accuracy at 0.874. Furthermore, an independent test
done involving data not included in the cross-validation process indicates that in silico identification is a feasible means of preliminary analysis. Additionally, the predictive method presented in this work is
implemented as Carboxylator (), a web-based tool for identifying carboxylated proteins with modification sites in order to help users in investigating
γ-glutamyl carboxylation. 相似文献
5.
Dr. Ashot Gevorgyan Prof. Dr. Kathrin H. Hopmann Prof. Dr. Annette Bayer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(27):6064-6069
A formal C−H carboxylation of unactivated arenes using CO2 in green solvents is described. The present strategy combines a sterically controlled Ir-catalyzed C−H borylation followed by a Cu-catalyzed carboxylation of the in situ generated organoboronates. The reaction is highly regioselective for the C−H carboxylation of 1,3-disubstituted and 1,2,3-trisubstituted benzenes, 1,2- or 1,4-symmetrically substituted benzenes, fluorinated benzenes and different heterocycles. The developed methodology was applied to the late-stage C−H carboxylation of commercial drugs and ligands. 相似文献
6.
The Renaissance of an Old Problem: Highly Regioselective Carboxylation of 2‐Alkynyl Bromides with Carbon Dioxide
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Bukeyan Miao Gen Li Prof. Dr. Shengming Ma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17224-17228
A steric effect‐controlled, zinc‐mediated carboxylation of different 2‐alkynyl bromides under an atmospheric pressure of CO2 has been developed by careful tuning of different reaction parameters, including the metal, solvent, temperature, and additive. 2‐Substituted 2,3‐allenoic acids were afforded from primary 2‐alkynyl bromides, whereas the carboxylation of secondary 2‐alkynyl bromides yielded 3‐alkynoic acids in decent yields. A rationale for the observed regioselectivity has been proposed. 相似文献
7.
Hidefumi Hirai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1491-1500
Terephthalic acid was synthesized by the carboxylation of benzoic acid with carbon tetrachloride in aqueous sodium hydroxide solution in the presence of cyclodextrin (CyD) and copper powder as catalyst. By the use of β-CyD at the initial molar ratio to benzoic acid of 0.5, the carboxylation at 60 °C for 7 hours produced terephthalic acid in 75 mol% yield with 87% selectivity. The selective synthesis of 4,4'-biphenyldicarboxylic acid in 70 mol% yield was achieved by the carboxylation of 4-biphenylcarboxylic acid with carbon tetrachloride in the presence of β-Cyd under similar conditions. The carboxylation of 2-naphthalene carboxylic acid with carbon tetrachloride using β-Cyd under similar conditions produced 2,6-naphthalenedicarboxylic acid in 67 mol% yield with 84% selectivity. When α-CyD and γ-CyD were used in place of β-Cyd, both the yields and the selectivities of the dicarboxylic acids were markedly small. In the absence of CyD, carboxylation did not proceed. Inclusion complex formations between β-Cyd and aromatic monocarboxylic acids were indicated by the 1H chemical shifts of the β-Cyd. The reaction mechanism was discussed on the basis of inclusion complex formation. 相似文献
8.
One of the most challenging transformations in current organic chemistry is the catalytic carboxylation of a C(sp(3))-H bond using CO(2) gas, an inexpensive and ubiquitous C1 source. A sequential protocol for C(sp(3))-H carboxylation by employing a nitrogen-directed, metal-assisted, C-H activation/catalytic silylation reaction in conjunction with fluoride-mediated carboxylation with CO(2) was established. The carboxylation proceeded only at the benzylic C(sp(3))-Si bond, not at the aromatic C(sp(2))-Si, which is advantageous for further manipulations of the products. 相似文献
9.
A nickel-catalyzed reductive carboxylation of styrenes using CO2 has been developed. The reaction proceeds under mild conditions using diethylzinc as the reductant. Preliminary data suggests the mechanism involves two discrete nickel-mediated catalytic cycles, the first involving a catalyzed hydrozincation of the alkene followed by a second, slower nickel-catalyzed carboxylation of the in situ formed organozinc reagent. Importantly, the catalyst system is very robust and will fixate CO2 in good yield even if exposed to only an equimolar amount introduced into the headspace above the reaction. 相似文献
10.
吴兆轩 Heriberto Diaz Velazquez 闵梦蝶 原晔 Hussein A. Younus 陈建 Bibimaryam Mousavi Francis Verpoort 《化学通报》2015,78(3):220-225
近年来,催化CO2合成精细化学品的研究备受关注。本研究在温和条件下利用金属双氮杂环卡宾催化剂实现CO2与末端炔烃的直接羧化反应,并提出合理的催化机理。首先,合成制备了铜基、银基两种金属双氮杂环卡宾催化剂,实验证明银双氮杂环卡宾配合物具有较好催化活性。通过改变环境条件和底物种类,对反应条件及催化剂底物适应性进行了探究,利用核磁共振谱仪表征产物分子结构并计算直接羧化反应的催化产率。结果表明,适宜催化条件为:1.2eq Cs2CO3作为添加剂、1大气压、室温、无水溶剂和1(mmol)%催化剂用量。银基金属催化剂活性较铜基催化剂高并具有广泛的底物适应性,对苯乙炔的催化产率高达93%;对乙炔气体同样具有良好的催化活性。此类催化剂具有优良的催化活性,能催化合成丙炔酸等重要医药中间体,在工业应用上具有极大潜力和广阔前景。 相似文献
11.
A Pd(II)-catalyzed reaction protocol for the direct carboxylation of benzoic and phenylacetic acid derivatives to form dicarboxylic acids has been developed. The reaction conditions are also applicable for the carboxylation of vinyl C-H bonds. The first C-H insertion Pd-aryl complex from carboxylic acids has been characterized by X-ray crystallography. 相似文献
12.
Studies carried out in the past two years on electrochemical fixation of carbon dioxide with carbon-carbon bond formation, so-called electrochemical carboxylation or electrocarboxylation, are reviewed. Among about twenty papers on electrochemical carboxylation published from 2014 to the present, recent advances in electrochemical carboxylation regarding asymmetric carboxylation, sacrificial anode-free carboxylation, and carboxylation following aryl radical cyclization are focused on and discussed. 相似文献
13.
A simple and efficient electrocatalytic carboxylation of arylic bromides has been developed using silver as cathode and magnesium as anode in N,N-dimethylformamide (DMF) under mild conditions. The influences of some key factors (such as the nature of cathode material, current density, and temperature) on this reaction were investigated. The investigations were extended to other arylic bromides under the optimized conditions, and the corresponding carboxylic acids were obtained in moderate to good yields (30–78%). The electrochemical behavior was studied at different electrodes (Ag, Cu, Ni, and Ti) by cyclic voltammetry, which showed significant electrocatalytic effect of the silver electrode toward the reductive carboxylation of arylic bromides. 相似文献
14.
A convenient approach to selectively prepare a wide range of functionalized propiolic acids was developed by AgI-catalyzed carboxylation of terminal alkynes using carbon dioxide as carboxylative agent under ligand-free conditions. 相似文献
15.
Chun‐Xiao Guo Dr. Wen‐Zhen Zhang Dr. Hui Zhou Ning Zhang Prof. Dr. Xiao‐Bing Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17156-17159
A straightforward and transition‐metal‐free approach for the efficient synthesis of α‐arylglycine derivatives from aromatic imines and carbon dioxide was enabled by an umpolung carboxylation reaction. Various substituted diphenylmethimines underwent the carboxylation smoothly with carbon dioxide in the presence of potassium tert‐butoxide and 18‐crown‐6 to give the corresponding carboxylated products in good to high yields. Besides the enhancement of the solubility of potassium tert‐butoxide in THF, 18‐crown‐6 also plays key roles in suppressing the reverse protonation or 1, 3‐proton shift isomerization as well as by stabilizing the carboxylated intermediate. 相似文献
16.
Cu‐Catalyzed Alkylative Carboxylation of Ynamides with Dialkylzinc Reagents and Carbon Dioxide
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Dr. Masanori Takimoto Sandeep Suryabhan Gholap Prof. Dr. Zhaomin Hou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15218-15223
Alkylative carboxylation of ynamides with CO2 and dialkylzinc reagents using a N‐heterocyclic carbene (NHC)–copper catalyst has been developed. A variety of ynamides, both cyclic and acyclic, undergo this transformation under mild conditions to afford the corresponding α,β‐unsaturated carboxylic acids, which contain the α,β‐dehydroamino acid skeleton. The present alkylative carboxylation formally consists of Cu‐catalyzed carbozincation of ynamides with dialkylzinc reagents with the subsequent nucleophilic carboxylation of the resulting alkenylzinc species with CO2. Dialkylzinc reagents bearing a β‐hydrogen atom such as Et2Zn and Bu2Zn still afford the alkylated products despite the potential for β‐hydride elimination. This protocol would be a desirable method for the synthesis of highly substituted α,β‐ dehydroamino acid derivatives due to its high regio‐ and stereoselectivity, simple one‐pot procedure, and its use of CO2 as a starting material. 相似文献
17.
Yang Wang Vladimir Gevorgyan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(7):2283-2287
A silanol‐directed, palladium‐catalyzed C H carboxylation reaction of phenols to give salicylic acids has been developed. This method features high efficiency and selectivity, and excellent functional‐group tolerance. The generality of this method was demonstrated by the carboxylation of estrone and by the synthesis of an unsymmetrically o,o′‐disubstituted phenolic compound through two sequential C H functionalization processes. 相似文献
18.
Dr. Naoki Ishida Yusuke Masuda Sho Uemoto Prof. Dr. Masahiro Murakami 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(19):6524-6527
A photo‐induced carboxylation reaction of allylic C?H bonds of simple alkenes with CO2 is prompted by means of a ketone and a copper complex. The unique carboxylation reaction proceeds through a sequence of an endergonic photoreaction of ketones with alkenes forming homoallyl alcohol intermediates and a thermal copper‐catalyzed allyl transfer reaction from the homoallyl alcohols to CO2 through C?C bond cleavage. 相似文献
19.
General Method for the Synthesis of Salicylic Acids from Phenols through Palladium‐Catalyzed Silanol‐Directed CH Carboxylation
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Yang Wang Prof. Dr. Vladimir Gevorgyan 《Angewandte Chemie (International ed. in English)》2015,54(7):2255-2259
A silanol‐directed, palladium‐catalyzed C? H carboxylation reaction of phenols to give salicylic acids has been developed. This method features high efficiency and selectivity, and excellent functional‐group tolerance. The generality of this method was demonstrated by the carboxylation of estrone and by the synthesis of an unsymmetrically o,o′‐disubstituted phenolic compound through two sequential C? H functionalization processes. 相似文献
20.
The ethyl esters of pyridine carboxylic acids were obtained by reaction of the ethoxycarbonyl radical with methyl-substituted pyridines. A mechanism is proposed for the carboxylation reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 224–225, February, 1976. 相似文献