838-58-4Relevant academic research and scientific papers
Carboxylic acid addition to terminal alkynes utilizing ammonium tagged Hoveyda-Grubbs catalyst supported on magnetically separable core/shell silica: A highly reusable and air compatible catalytic system
?ztürk, Bengi ?zgün,Gürcü, Didar,?ehito?lu, Solmaz Karabulut
, p. 11 - 16 (2019/01/24)
In this study, the performance of ammonium tagged Hoveyda-Grubbs catalyst supported on magnetically separable core/shell silica gel was tested on carboxylic acid addition reactions to terminal alkynes using a variety of carboxylic acid derivatives under air atmosphere. The catalytic system was found to be compatible with air atmosphere and can tolerate even non-degassed solvents. The reaction parameters such as temperature, substrate/catalyst ratio and the effect of carboxylic acid on the selectivity and yield of the reaction were investigated in details. The reaction of arylacetylenes with acetic acid yielded the corresponding E-isomer with conversion values up to 99% with a catalytic loading of 1% Ru. The reusability of the catalyst was tested using acetic acid/benzoic acid and phenylacetylene in toluene at 85 °C under air atmosphere. The catalyst was found to be highly reusable and maintained its activity up to 11th run, reaching a conversion value of 83% with minimum ruthenium leaching.
Cationic ruthenium complex of the formula [RuCl(2,6-diacetylpyridine)(PPh3)2]BArF and its catalytic activity in the formation of enol esters
Stark, Matthew J.,Tang, Douglas T.,Rath, Nigam P.,Bauer, Eike B.
supporting information, p. 873 - 877 (2018/02/09)
A new ruthenium 2,6-diacetylpyridine complex was synthesized and applied in the atom-economic synthesis of enol esters through Markovnikov-directed addition of carboxylic acids to terminal alkynes. The ruthenium complex [RuCl(dap)(PPh3)2]+BArF? was synthesized from [RuCl2(PPh3)2] and the corresponding ligand 2,6-diacetylpyridine (dap). The complex was characterized structurally. The new ruthenium complex was utilized under ambient conditions as a catalyst in the Markovnikov addition of carboxylic acids to terminal alkynes to afford the corresponding enol esters in 93% to 52% isolated yields (85 °C, 16 h reaction time, 1 mol% catalyst loading).
Enol Ester Synthesis via Cobalt-Catalyzed Regio- and Stereoselective Addition of Carboxylic Acids to Alkynes
Chen, Jia-Feng,Li, Changkun
supporting information, p. 6719 - 6724 (2018/11/21)
A cobalt-catalyzed highly regio- and stereoselective hydro-oxycarbonylation of alkynes is reported. Both terminal and internal alkynes can react with carboxylic acids to afford enol esters in high yields. The catalyst generated from Co(BF4)2, tridentate phosphine ligand L5, and zinc in situ exhibits much higher reactivity than the corresponding cobalt/diphosphine complex.
Regioselective Formation of Enol Esters from the Ruthenium-Catalyzed Markovnikov Addition of Carboxylic Acids to Alkynes
Jeschke, Janine,G?bler, Christian,Lang, Heinrich
supporting information, p. 476 - 484 (2016/01/25)
The ruthenium complexes [Ru(CO)2(P(p-C6H4-X)3)2(O2CPh)2] (1a, X = CF3; 1b, X = Cl; 1c, X = H; 1d, X = Me; 1e, X = OMe) were successfully applied in the regioselective Markovnikov addition of carboxylic acids to terminal alkynes, yielding valuable enol esters. Catalyst screening revealed a significant influence of phosphine's electronic nature on activity and selectivity. The highest activity was achieved with catalyst 1a, featuring the most electron-withdrawing phosphine ligand. Selectivity and activity could be further improved by the addition of catalytic amounts of AgOTf. Moreover, excellent selectivities with up to 99% of the Markovnikov product were achieved. The electronic influence of the substrates on the reaction rate was quantified by Hammett plots. By the use of electron-rich alkynes or highly acidic carboxylic acids, the reaction rate could be increased. Hence, the addition of highly acidic pentafluorobenzoic acid to electron-rich 4-methoxyphenylacetylene can even be carried out quantitatively at 25°C within 4 h. Furthermore, a broad range of simple as well as electronically or sterically challenging substrates could be isolated in good to excellent yields with high regioselectivity and under mild reaction conditions (25-70°C). The best reported activities and selectivities were obtained for the conversion of aromatic alkynes.
Alkyne reactions with trimethylphosphine complexes of iridium: Lessons for the catalysis of vinyl ester formation and alkyne dimerization
Merola, Joseph S.,Ladipo, Folami T.
, p. 125 - 132 (2014/02/14)
The combination of iridium with trimethylphosphine ligands yields very electron rich iridium compounds that are active for terminal alkyne dimerization chemistry as well as the addition of carboxylic acids to alkynes. The structures, catalytic and stoichi
Asymmetric hydrogenation of 1-alkyl and 1-aryl vinyl benzoates: A broad scope procedure for the highly enantioselective synthesis of 1-substituted ethyl benzoates
Kleman, Patryk,Gonzlez-Liste, Pedro J.,Garca-Garrido, Sergio E.,Cadierno, Victorio,Pizzano, Antonio
, p. 4398 - 4408 (2015/02/05)
The enantioselective hydrogenation of enol esters of formula CH2=C(OBz)R with rhodium catalysts based on phosphine-phosphite ligands (P-OP) has been studied. The reaction has a broad scope, and it is suitable for the preparation of products pos
Highly enantioselective hydrogenation of 1-alkylvinyl benzoates: A simple, nonenzymatic access to chiral 2-alkanols
Kleman, Patryk,González-Liste, Pedro J.,García-Garrido, Sergio E.,Cadierno, Victorio,Pizzano, Antonio
supporting information, p. 16209 - 16212 (2013/12/04)
Going chiral! Highly enantioselective catalytic hydrogenations of enol esters 1 by using a Rh catalyst bearing a P?￡?OP ligand are described (see scheme; NBD=norbornadiene). The catalytic system has a broad scope and allows the preparation of a wide range of chiral esters 2 bearing diverse alkyls or a benzyl group with high enantioselectivities. These esters can easily be converted in highly enantioenriched 2-alkanols. Copyright
Steric control at the wingtip of a bis-N-heterocyclic carbene ligand: Coordination behavior and catalytic responses of its ruthenium compounds
Saha, Sayantani,Ghatak, Tapas,Saha, Biswajit,Doucet, Henri,Bera, Jitendra K.
, p. 5500 - 5505 (2012/11/07)
Changing the N-substituents of a methylene-linked bis-NHC ligand from n-butyl to bulky mesityl shifts ligand coordination from normal/normal to normal/abnormal mode. The mesityl wingtip groups afford [RuII( MesNHC(CH2)NHC
Synthesis and structure of [Ru(dppe)2(CH3CN)Cl] [BPh4] and its catalytic application to anti-Markovnikov addition of carboxylic acids to terminal alkynes
Das, Uttam Kumar,Bhattacharjee, Manish
experimental part, p. 78 - 82 (2012/03/12)
The compound, [Ru(dppe)2(CH3CN)Cl][BPh4] (1) has been synthesized from the precursor complex, [(PPh3) 2Ru(CH3CN)3Cl][BPh4]. The complex has been structurally character
Ruthenium(IV)-catalyzed markovnikov addition of carboxylic acids to terminal alkynes in aqueous medium
Cadierno, Victorio,Francos, Javier,Gimeno, Jose
experimental part, p. 852 - 862 (2011/04/15)
The dimeric bis(allyl)ruthenium(IV) complex [{RuCl(μ-Cl)( η3:η3-C10H16)}2] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl) (5) and several mononuclear species trans-[RuCl2(η3: η3-C10H16)(L)] (L = two-electron-donor ligand) (6) derived from 5 have been checked as catalysts for the addition of carboxylic acids onto terminal alkynes using water as a green reaction medium. The best results in terms of activity and regioselectivity were obtained with the mononuclear derivative trans-[RuCl2(η3: η3-C10H16)(PPh3)] (6a), which was able to promote the selective Markovnikov addition of both aromatic and aliphatic carboxylic acids to a large variety of terminal alkynes, enynes, and diynes as well as propargylic alcohols. In this way, a wide number of enol esters and β-oxo esters could be synthesized in moderate to good yields under mild conditions (60 °C) in an aqueous medium.
