- Visible-light photoredox-catalyzed selective carboxylation of C(sp3)?F bonds with CO2
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It is highly attractive and challenging to utilize carbon dioxide (CO2), because of its inertness, as a nontoxic and sustainable C1 source in the synthesis of valuable compounds. Here, we report a novel selective carboxylation of C(sp3)?F bonds with CO2 via visible-light photoredox catalysis. A variety of mono-, di-, and trifluoroalkylarenes as well as α,α-difluorocarboxylic esters and amides undergo such reactions to give important aryl acetic acids and α-fluorocarboxylic acids, including several drugs and analogs, under mild conditions. Notably, mechanistic studies and DFT calculations demonstrate the dual role of CO2 as an electron carrier and electrophile during this transformation. The fluorinated substrates would undergo single-electron reduction by electron-rich CO2 radical anions, which are generated in situ from CO2 via sequential hydride-transfer reduction and hydrogen-atom-transfer processes. We anticipate our finding to be a starting point for more challenging CO2 utilization with inert substrates, including lignin and other biomass.
- Bo, Zhi-Yu,Chen, Lin,Gao, Tian-Yu,Jing, Ke,Lan, Yu,Liu, Shi-Han,Luo, Shu-Ping,Yan, Si-Shun,Yu, Bo,Yu, Da-Gang
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supporting information
p. 3099 - 3113
(2021/11/16)
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- Ligand-Controlled Regioselective Hydrocarboxylation of Styrenes with CO2 by Combining Visible Light and Nickel Catalysis
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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.
- Meng, Qing-Yuan,Wang, Shun,Huff, Gregory S.,Konig, Burkhard
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supporting information
p. 3198 - 3201
(2018/03/13)
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- Construction of a visible light-driven hydrocarboxylation cycle of alkenes by the combined use of Rh(i) and photoredox catalysts
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A visible light driven catalytic cycle for hydrocarboxylation of alkenes with CO2 was established using a combination of a Rh(i) complex as a carboxylation catalyst and [Ru(bpy)3]2+ (bpy = 2,2′- bipyridyl) as a photoredox catalyst. Two key steps, the generation of Rh(i) hydride species and nucleophilic addition of π-benzyl Rh(i) species to CO2, were found to be mediated by light.
- Murata, Kei,Numasawa, Nobutsugu,Shimomaki, Katsuya,Takaya, Jun,Iwasawa, Nobuharu
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supporting information
p. 3098 - 3101
(2017/03/17)
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- Rhodium-Catalyzed Hydrocarboxylation of Olefins with Carbon Dioxide
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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.
- Kawashima, Shingo,Aikawa, Kohsuke,Mikami, Koichi
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p. 3166 - 3170
(2016/07/19)
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- Nickel-Catalyzed Carboxylation of Benzylic C-N Bonds with CO2
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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.
- Moragas, Toni,Gaydou, Morgane,Martin, Ruben
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supporting information
p. 5053 - 5057
(2016/04/26)
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- METHOD OF PRODUCING CARBOXYLATE
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PROBLEM TO BE SOLVED: To provide a method of producing useful chemicals of carboxylates through hydrocarboxylation reaction of olefins by effectively utilizing carbon dioxide without using any expensive reducing agent. SOLUTION: A method of producing a carboxylate represented by the general formula (3) includes reacting an olefin with a formate represented by the general formula (2). (An+ is an n-valent cation; n is an integer from 1 to 4; and R1 to R4 are each independently H or a C1-24 organic group, where two or more of the R1 to R4 may be connected with each other.) SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0062-0064
(2018/10/16)
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- Electrochemical direct carboxylation of benzyl alcohols having an electron-withdrawing group on the phenyl ring: One-step formation of phenylacetic acids from benzyl alcohols under mild conditions
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Electrochemical direct carboxylation of benzyl alcohols having an electron-withdrawing group on the phenyl ring was successfully carried out by constant current electrolysis using an undivided cell equipped with a platinum plate cathode and a magnesium rod anode in DMF in the presence of carbon dioxide. Reductive cleavage of the C-O bond followed by fixation of carbon dioxide efficiently took place at the benzylic position without any additive to give the corresponding phenylacetic acids in good yields in one step under neutral and mild conditions.
- Senboku, Hisanori,Yoneda, Kenji,Hara, Shoji
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p. 6772 - 6776
(2016/01/30)
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- Beyond benzyl grignards: Facile generation of benzyl carbanions from styrenes
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Benzylic functionalization is a convenient approach towards the conversion of readily available aromatic hydrocarbon feedstocks into more useful molecules. However, the formation of carbanionic benzyl species from benzyl halides or similar precursors is far from trivial. An alternative approach is the direct reaction of a styrene with a suitable coupling partner, but these reactions often involve the use of precious-metal transition-metal catalysts. Herein, we report the facile and convenient generation of reactive benzyl anionic species from styrenes. A CuI-catalyzed Markovnikov hydroboration of the styrenic double bond by using a bulky pinacol borane source is followed by treatment with KOtBu to facilitate a sterically induced cleavage of the C-B bond to produce a benzylic carbanion. Quenching this intermediate with a variety of electrophiles, including CO2, CS2, isocyanates, and isothiocyanates, promotes C-C bond formation at the benzylic carbon atom. The utility of this methodology was demonstrated in a three-step, two-pot synthesis of the nonsteroidal anti-inflammatory drug (±)-flurbiprofen. Make or break: The facile generation of benzyl anion equivalents from styrenes has been achieved by using a Cu-catalyzed hydroboration in conjunction with sterically induced cleavage of the C-B bond with tBuOK. Quenching this reactive intermediate with heteroallene electrophiles yields benzylic C-C bond formation (see scheme), and the utility of this methodology has been demonstrated by a synthesis of the nonsteroidal anti-inflammatory drug (±)-flurbiprofen. Copyright
- Grigg, R. David,Rigoli, Jared W.,Van Hoveln, Ryan,Neale, Samuel,Schomaker, Jennifer M.
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p. 9391 - 9396
(2012/08/29)
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- Electrochemical carboxylation of benzylic carbonates: Alternative method for efficient synthesis of arylacetic acids
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Electrochemical carboxylation of benzylic carbonates was successfully performed as an alternative method for the synthesis of phenylacetic acids by using a one-compartment cell equipped with a Pt plate cathode and an Mg rod anode in CH3CN to afford the corresponding phenylacetic acids in good yields.
- Ohkoshi, Masashi,Michinishi, Jun-Ya,Hara, Shoji,Senboku, Hisanori
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experimental part
p. 7732 - 7737
(2010/10/21)
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- Nickel-catalyzed reductive carboxylation of styrenes using CO2
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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. Copyright
- Williams, Catherine M.,Johnson, Jeffrey B.,Rovis, Tomislav
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supporting information; experimental part
p. 14936 - 14937
(2009/03/12)
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