41387-29-5Relevant academic research and scientific papers
Site-Selective, Remote sp3 C?H Carboxylation Enabled by the Merger of Photoredox and Nickel Catalysis
Sahoo, Basudev,Bellotti, Peter,Juliá-Hernández, Francisco,Meng, Qing-Yuan,Crespi, Stefano,K?nig, Burkhard,Martin, Ruben
supporting information, p. 9001 - 9005 (2019/06/24)
A photoinduced carboxylation of alkyl halides with CO2 at remote sp3 C?H sites enabled by the merger of photoredox and Ni catalysis is described. This protocol features a predictable reactivity and site selectivity that can be modulated by the ligand backbone. Preliminary studies reinforce a rationale based on a dynamic displacement of the catalyst throughout the alkyl side chain.
Ligand-Controlled Regioselective Hydrocarboxylation of Styrenes with CO2 by Combining Visible Light and Nickel Catalysis
Meng, Qing-Yuan,Wang, Shun,Huff, Gregory S.,Konig, Burkhard
supporting information, p. 3198 - 3201 (2018/03/13)
The ligand-controlled Markovnikov and anti-Markovnikov hydrocarboxylation of styrenes with atmospheric pressure of CO2 at room temperature using dual visible-light-nickel catalysis has been developed. In the presence of neocuproine as ligand, the Markovnikov product is obtained exclusively, while employing 1,4-bis(diphenylphosphino)butane (dppb) as the ligand favors the formation of the anti-Markovnikov product. A range of functional groups and electron-poor, -neutral, as well as electron-rich styrene derivatives are tolerated by the reaction, providing the desired products in moderate to good yields. Preliminary mechanistic investigations indicate the generation of a nickel hydride (H-NiII) intermediate, which subsequently adds irreversibly to styrenes.
Rhodium-Catalyzed Hydrocarboxylation: Mechanistic Analysis Reveals Unusual Transition State for Carbon-Carbon Bond Formation
Pavlovic, Ljiljana,Vaitla, Janakiram,Bayer, Annette,Hopmann, Kathrin H.
supporting information, p. 941 - 948 (2018/03/30)
The mechanism of rhodium-COD-catalyzed hydrocarboxylation of styrene derivatives and α,β-unsaturated carbonyl compounds with CO2 has been investigated using density functional theory (PBE-D2/IEFPCM). The calculations support a catalytic cycle as originally proposed by Mikami and co-workers including β-hydride elimination, insertion of the unsaturated substrate into a rhodium-hydride bond, and subsequent carboxylation with CO2. The CO2 insertion step is found to be rate limiting. The calculations reveal two interesting aspects. First, during C-CO2 bond formation, the CO2 molecule interacts with neither the rhodium complex nor the organozinc additive. This appears to be in contrast to other CO2 insertion reactions, where CO2-metal interactions have been predicted. Second, the substrates show an unusual coordination mode during CO2 insertion, with the nucleophilic carbon positioned up to 3.6 ? away from rhodium. In order to understand the experimentally observed substrate preferences, we have analyzed a set of five alkenes: an α,β-unsaturated ester, an α,β-unsaturated amide, styrene, and two styrene derivatives. The computational results and additional experiments reported here indicate that the lack of activity with amides is caused by an overly high barrier for CO2 insertion and is not due to catalyst inactivation. Our experimental studies also reveal two putative side reactions, involving oxidative cleavage or dimerization of the alkene substrate. In the presence of CO2, these alternative reaction pathways are suppressed. The overall insights may be relevant for the design of future hydrocarboxylation catalysts.
Rhodium-Catalyzed Hydrocarboxylation of Olefins with Carbon Dioxide
Kawashima, Shingo,Aikawa, Kohsuke,Mikami, Koichi
, p. 3166 - 3170 (2016/07/19)
The catalytic hydrocarboxylation of styrenes derivatives and α,β-unsaturated carbonyl compounds with CO2(101.3 kPa) in the presence of an air-stable rhodium catalyst was explored. The combination of [RhCl(cod)]2(cod = cyclooctadiene) as a catalyst and diethylzinc as a hydride source allowed for effective hydrocarboxylation and provided the corresponding α-aryl carboxylic acids in moderate to excellent yields. In this catalytic process with carbon dioxide, intervention of the RhI–H species, which could be generated from the RhIcatalyst and diethylzinc, was clarified. Significantly, the catalytic asymmetric hydrocarboxylation of α,β-unsaturated esters with carbon dioxide was also performed by employing a cationic rhodium complex possessing (S)-(–)-4,4′-bi-1,3-benzodioxole-5,5′-diylbis(diphenylphosphine) [(S)-SEGPHOS] as a chiral diphosphine ligand. A plausible model for asymmetric induction was proposed by determination of the absolute configuration of the product.
Anchored Pd-complexes in mesoporous supports: Synthesis, characterization and catalysis studies for carbonylation reactions
Sarkar, Bibhas R.,Chaudhari, Raghunath V.
, p. 154 - 173 (2013/01/15)
Pd(pyca)(PPh3)(OTs) [pyca = 2-picolinate] complex is efficiently anchored inside different mesoporous matrices, such as MCM-41, MCM-48, SBA-15 using a molecular aminopropyl tether moiety employing different synthesis strategies. Thorough characterization of the materials using powder XRD, multinuclear (13C, 29Si, 31P) CP-MAS NMR, XPS, SEM, N2-sorption studies etc. confirmed the successful anchoring of the palladium complex to the walls of the support matrices thus establishing the synthesis protocols unambiguously. The catalysts were found to be highly active and selective for the carbonylation of different aryl olefins and alcohols. Consecutive recycling and successful reuse proved the stability and true heterogeneous nature of all the anchored catalysts, which is a substantial advancement over the existing heterogeneous catalysts for carbonylation.
Tempo-mediated oxidation of primary alcohols to carboxylic acids by exploitation of ethers inan aqueous-organicbiphase system
Mei, Zhen-Wu,Ma, Li-Jian,Kawafuchi, Hiroyuki,Okihara, Takumi,Inokuchi, Tsutomu
experimental part, p. 1000 - 1002 (2011/03/22)
Expeditious and benign methods for primary alcohol- carboxylicacid conversions with TEMPO were developed in abiphasic system composed of aslightlymiscible ether (THP) and aqueous layer. Easily available co-oxidants such as Py-HBr3, Bu4NBr3, and electrooxidation were successfully applied to generate N-oxoammonium species as a recyclable catalyst.
Oxidative Rearrangement of Alkynes to Carboxylic Acid Esters by benzene in Methanol
Moriarty, Robert M.,Vaid, Radhe K.,Duncan, Michael P.,Vaid, Beena K.
, p. 2845 - 2848 (2007/10/02)
A direct synthesis of methyl aryl alkanoate via oxidative rearrangement of alkynes using benzene in methanol is described.
