689-89-4Relevant academic research and scientific papers
Enantioselective and Diastereodivergent Synthesis of Spiroindolenines via Chiral Phosphoric Acid-Catalyzed Cycloaddition
Gandon, Vincent,Masson, Géraldine,Mati?i?, Mateja,Neuville, Luc,Van Elslande, Elsa,Varlet, Thomas
supporting information, p. 11611 - 11619 (2021/08/16)
A diastereodivergent and enantioselective synthesis of chiral spirocyclohexyl-indolenines with four contiguous stereogenic centers is achieved by a chiral phosphoric acid-catalyzed cycloaddition of 2-susbtituted 3-indolylmethanols with 1,3-dienecarbamates. Modular access to two different diastereoisomers with high enantioselectivities was obtained by careful choice of reaction conditions. Their functional group manipulation provides an efficient access to enantioenriched spirocyclohexyl-indolines and -oxindoles. The origins of this stereocontrol have been identified using DFT calculations, which reveal an unexpected mechanism compared to our previous work dealing with enecarbamates.
Ruthenium-Catalyzed Oxidative Cross-Coupling Reaction of Activated Olefins with Vinyl Boronates for the Synthesis of (E, E)-1,3-Dienes
Dethe, Dattatraya H.,Beeralingappa, Nagabhushana C.,Uike, Amar
, p. 3444 - 3455 (2021/02/16)
An oxidative cross-coupling reaction between activated olefins and vinyl boronate derivatives has been developed for the highly stereoselective construction of synthetically useful (E,E)-1,3-dienes. The highlight of this reaction is that exclusive stereoselectivity (only E,E-isomer) was achieved from a base-free, ligand-free, and mild catalytic condition with a less expensive [RuCl2(p-cymene)]2 catalyst.
Protection of COOH and OH groups in acid, base and salt free reactions
Zhu, Xiaotao,Qian, Bo,Wei, Rongbiao,Huang, Jian-Dong,Bao, Hongli
supporting information, p. 1444 - 1447 (2018/04/12)
We report an iron-catalyzed general functional group protection method with inexpensive reagents. This environmentally benign process does not use acids or bases, and does not produce waste products. Further purification beyond filtration and evaporation is, in most cases, unnecessary. Free COOH and OH groups can be protected in a one-pot reaction.
Efficient flow fischer esterification of carboxylic acids with alcohols using sulfonic acid-functionalized silica as supported catalyst
Furuta, Akihiro,Fukuyama, Takahide,Ryu, Ilhyong
, p. 607 - 612 (2017/06/19)
Flow Fischer esterification of carboxylic acids using hydroxy-substituted sulfonic acid-functionalized silica (HOSAS) packed into a stainless steel column reactor was investigated. HO-SAS well catalyzed flow esterification of long chain carboxylic acids with methanol within 3min of residence time at 110°C, and the methyl esters were quantitatively obtained. The flow esterification protocol was applied to the synthesis of a variety of esters (19 examples) and scalable synthesis was also successful.
Copper-Catalyzed O-Methylation of Carboxylic Acids Using DMSO as a Methyl Source
Jia, Jing,Jiang, Qing,Zhao, An,Xu, Bin,Liu, Qiang,Luo, Wei-Ping,Guo, Can-Cheng
, p. 421 - 428 (2016/01/28)
A copper-catalyzed O-methylation of carboxylic acids using dimethyl sulfoxide (DMSO) as the methyl source is disclosed. This transformation exhibits a broad substrate scope and excellent functional group tolerance. Mechanistic studies indicate that a methyl radical is generated from dimethyl sulfoxide in the reaction process.
Studies on [2?+?3] cycloaddition reaction of nitrile oxides to linear dipolarophiles bearing multiple double bonds
Gucma, Miros?aw,Go??biewski, W. Marek,Michalczyk, Alicja Katarzyna
, p. 1809 - 1818 (2016/09/28)
Abstract: Site selectivity, regioselectivity, and stereoselectivity of [2?+?3] cycloaddition of benzonitrile oxides to polyunsaturated esters were examined. Site selectivity was correlated with electron charges of unsaturated carbon atoms. Structure of the products has been established by an extensive application of 1H and 13C NMR spectroscopy and electrospray ionization mass spectrometry. Graphical abstract: [Figure not available: see fulltext.]
On the Functional Group Tolerance of Ester Hydrogenation and Polyester Depolymerisation Catalysed by Ruthenium Complexes of Tridentate Aminophosphine Ligands
Fuentes, José A.,Smith, Samuel M.,Scharbert, M. Theresa,Carpenter, Ian,Cordes, David B.,Slawin, Alexandra M. Z.,Clarke, Matthew L.
supporting information, p. 10851 - 10869 (2015/07/20)
The synthesis of a range of phosphine-diamine, phosphine-amino-alcohol, and phosphine-amino-amide ligands and their ruthenium(II) complexes are reported. Five of these were characterised by X-ray crystallography. The activities of this collection of catalysts were initially compared for the hydrogenation of two model ester hydrogenations. Catalyst turnover frequencies up to 2400 h-1 were observed at 85 °C. However, turnover is slow at near ambient temperatures. By using a phosphine-diamine RuII complex, identified as the most active catalyst, a range of aromatic esters were reduced in high yield. The hydrogenation of alkene-, diene-, and alkyne-functionalised esters was also studied. Substrates with a remote, but reactive terminal alkene substituent could be reduced chemoselectively in the presence of 4-dimethylaminopyridine (DMAP) co-catalyst. The chemoselective reduction of the ester function in conjugated dienoate ethyl sorbate could deliver (2E,4E)-hexa-2,4-dien-1-ol, a precursor to leaf alcohol. The monounsaturated alcohol (E)-hex-4-en-1-ol was produced with reasonable selectivity, but complete chemoselectivity of C=O over the diene is elusive. High chemoselectivity for the reduction of an ester over an alkyne group was observed in the hydrogenation of an alkynoate for the first time. The catalysts were also active in the depolymerisation reduction of samples of waste poly(ethylene terephthalate) (PET) to produce benzene dimethanol. These depolymerisations were found to be poisoned by the ethylene glycol side product, although good yields could still be achieved. A simple catalyst for difficult reductions: Ruthenium complexes of P,N,N and P,N,O ligands catalyse the reduction of esters with high activities. The Ru complex of a phosphine-diamine ligand (see scheme) has been found to be a good catalyst for reducing alkene-, diene-, and alkyne-functionalised esters, displaying good activity and chemoselectivity. This catalyst was also active in the hydrogenation of waste poly(ethylene terephthalate) (PET).
Extending the stetter reaction with 1,6-acceptors
Law, Katherine R.,McErlean, Christopher S. P.
supporting information, p. 15852 - 15855 (2014/04/03)
Pace Stetter: A new N-heterocyclic carbene (NHC)-catalysed transformation is described-the intramolecular vinylogous Stetter reaction. This transformation can be effected with both thiazolium and triazolium-based catalysts, using aromatic and aliphatic aldehydes, employing α,β,γ,δ- unsaturated esters, ketones, phosphonates and N-acylpyrroles, and can be conducted enantioselectively (see scheme). Copyright
New and concise syntheses of the bicyclic oxamazin core using an intramolecular nitroso diels-alder reaction and ring-closing olefin metathesis
Watson, Kyle D.,Carosso, Serena,Miller, Marvin J.
supporting information, p. 358 - 361 (2013/03/13)
Herein two new and concise synthetic approaches for making an unsaturated bicyclic oxamazin core are reported. The first involves the use of an intramolecular Diels-Alder reaction to form both of the fused rings in one step. The second approach incorporates ring-closing olefin metathesis in the final step to form the second fused ring of the core. The scope of the second approach was also expanded further to afford larger ringed bicyclic systems.
A novel catalytic asymmetric route towards skipped dienes with a methyl-substituted central stereogenic carbon
Huang, Yange,Fananas-Mastral, Martin,Minnaard, Adriaan J.,Feringa, Ben L.
supporting information, p. 3309 - 3311 (2013/06/04)
A highly efficient method for the enantioselective synthesis of 1,4-dienes (skipped dienes) with a methyl-substituted central stereogenic carbon using copper-catalysed asymmetric allylic alkylation of diene bromides was developed. Excellent regio- and enantioselectivity (up to 97 : 3 SN2′/ SN2 ratio and 99% ee) were achieved with broad substrate scope. The Royal Society of Chemistry 2013.
