4593-90-2Relevant academic research and scientific papers
Asymmetric conjugate addition reaction using pyrazole derivatives as a chiral catalyst
Kashima, Choji,Yokoyama, Hiroyo,Shibata, Saori,Fujisawa, Kiyoshi,Nishio, Takehiko
, p. 717 - 719 (2003)
The conjugate addition of Grignard reagent (2) onto 1-(α,β -unsaturated)acyl 3,5-dimethylpyrazole (1) was enantioselectively catalyzed by the copper complex from cuprous compounds and 3-phenyl-l-menthopyrazole (3).
Pd(II)-Catalyzed Pyridine N -Oxides Directed Arylation of Unactivated Csp3-H Bonds
Liu, Jianzhong,Xie, Ying,Zeng, Wei,Lin, Dongen,Deng, Yuanfu,Lu, Xiaoxia
, p. 4618 - 4626 (2015)
A novel Pd(II)-catalyzed pyridine N-oxide directed remote arylation of unactivated Csp3-H bonds in aliphatic amides with aryl iodides has been developed. This protocol allows installing various aryl groups at the β- or γ-Csp3 atom of alkyl carboxylic acid amides. The key palladabicyclic intermediate of this transformation has been identified by HR-MS and 1H NMR method. (Chemical Equation Presented).
Efficient asymmetric transfer hydrogenation of activated olefins catalyzed by ruthenium amido complexes
Chen, Ying-Chun,Xue, Dong,Deng, Jin-Gen,Cui, Xin,Zhu, Jin,Jiang, Yao-Zhong
, p. 1555 - 1558 (2004)
The asymmetric transfer hydrogenation of activated olefins with chiral ruthenium amido complexes (Noyori catalyst) using formic acid-triethylamine azeotrope as hydrogen source resulted in excellent yields and high enantioselectivities (up to 88.5%).
Photoredox Activation of Formate Salts: Hydrocarboxylation of Alkenes via Carboxyl Group Transfer
Huang, Yan,Hou, Jing,Zhan, Le-Wu,Zhang, Qian,Tang, Wan-Ying,Li, Bin-Dong
, p. 15004 - 15012 (2021/12/14)
A photoredox activation mode of formate salts for carboxylation was developed. Using a formate salt as the reductant, carbonyl source, and hydrogen atom transfer reagent, a wide range of alkenes can be converted into acid products via a carboxyl group tra
Chemoselective reduction of ?,￠-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
, p. 590 - 599 (2021/03/29)
The selective reduction of ?,￠-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ￠ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ￠-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
Asymmetric conjugate addition reactions with chiral oxadiazinones: Unusual conformational properties of the oxadiazinones
Obe, Fatima Olayemi,Davis, Ryan A.,Spurlock, Jennifer,Grunloh Barnes, Morgan M.,Lindvall, Tyler,Wendorf, Micah S.,Delach, Christina,Ferrence, Gregory M.,Standard, Jean M.,Hitchcock, Shawn R.
, (2021/02/26)
A series of Ephedra based oxadiazinones have been prepared, acylated, and examined in the asymmetric conjugate addition reaction with Grignard reagents in the presence of copper(I) bromide-dimethyl sulfide complex. The highest diastereoselectivity that was obtained in the conjugate addition reaction was observed with the (1R,2S)-ephedrine based N4-methyloxadiazinone (5:1 d.r.) favoring the formation of the (S)-configuration of the conjugate addition product. Efforts to enhance the level of diastereoselection via increasing the steric volume of the stereo-directing N4-substituent of the oxadiazinone (N4- = p-methoxyphenyl or -isopropyl) led to an observed decrease in the level of diastereoselection. A computational study was conducted to examine the conformations adopted by the N4-methyloxadiazinone vs. the N4-isopropyl-oxadiazinone that yielded the lower diastereoselectivity. An argument is made for the stereoelectronic properties of the N4-substituent being the cause of both the moderate diastereoselectivity and the unexpected facial preference for the conjugate addition.
Photoinduced Hydrocarboxylation via Thiol-Catalyzed Delivery of Formate across Activated Alkenes
Alektiar, Sara N.,Wickens, Zachary K.
supporting information, p. 13022 - 13028 (2021/09/03)
Herein we disclose a new photochemical process to prepare carboxylic acids from formate salts and alkenes. This redox-neutral hydrocarboxylation proceeds in high yields across diverse functionalized alkene substrates with excellent regioselectivity. This operationally simple procedure can be readily scaled in batch at low photocatalyst loading (0.01% photocatalyst). Furthermore, this new reaction can leverage commercially available formate carbon isotologues to enable the direct synthesis of isotopically labeled carboxylic acids. Mechanistic studies support the working model involving a thiol-catalyzed radical chain process wherein the atoms from formate are delivered across the alkene substrate via CO2?- as a key reactive intermediate.
CuH-Catalyzed Asymmetric Reductive Amidation of α,β-Unsaturated Carboxylic Acids
Link, Achim,Zhou, Yujing,Buchwald, Stephen L.
supporting information, p. 5666 - 5670 (2020/07/24)
The direct enantioselective copper hydride (CuH)-catalyzed synthesis of β-chiral amides from α,β-unsaturated carboxylic acids and secondary amines under mild reaction conditions is reported. The method utilizes readily accessible carboxylic acids and tolerates a variety of functional groups in the β-position including several heteroarenes. A subsequent iridium-catalyzed reduction to γ-chiral amines can be performed in the same flask without purification of the intermediate amides.
Cobalt-Catalyzed Asymmetric Hydrogenation of α,β-Unsaturated Carboxylic Acids by Homolytic H2 Cleavage
Chirik, Paul J.,Shevlin, Michael,Zhong, Hongyu
supporting information, (2020/03/13)
The asymmetric hydrogenation of α,β-unsaturated carboxylic acids using readily prepared bis(phosphine) cobalt(0) 1,5-cyclooctadiene precatalysts is described. Di-, tri-, and tetra-substituted acrylic acid derivatives with various substitution patterns as well as dehydro-α-amino acid derivatives were hydrogenated with high yields and enantioselectivities, affording chiral carboxylic acids including Naproxen, (S)-Flurbiprofen, and a d-DOPA precursor. Turnover numbers of up to 200 were routinely obtained. Compatibility with common organic functional groups was observed with the reduced cobalt(0) precatalysts, and protic solvents such as methanol and isopropanol were identified as optimal. A series of bis(phosphine) cobalt(II) bis(pivalate) complexes, which bear structural similarity to state-of-the-art ruthenium(II) catalysts, were synthesized, characterized, and proved catalytically competent. X-band EPR experiments revealed bis(phosphine)cobalt(II) bis(carboxylate)s were generated in catalytic reactions and were identified as catalyst resting states. Isolation and characterization of a cobalt(II)-substrate complex from a stoichiometric reaction suggests that alkene insertion into the cobalt hydride occurred in the presence of free carboxylic acid, producing the same alkane enantiomer as that from the catalytic reaction. Deuterium labeling studies established homolytic H2 (or D2) activation by Co(0) and cis addition of H2 (or D2) across alkene double bonds, reminiscent of rhodium(I) catalysts but distinct from ruthenium(II) and nickel(II) carboxylates that operate by heterolytic H2 cleavage pathways.
Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids**
Deng, Ruohan,Engle, Keary M.,Fu, Yue,Gao, Yang,Li, Zi-Qi,Liu, Peng,Tran, Van T.
supporting information, p. 23306 - 23312 (2020/10/19)
A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99 % yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state.
