26672-58-2Relevant academic research and scientific papers
Cobalt-Catalyzed Migrational Isomerization of Styrenes
Zhao, Jiajin,Cheng, Biao,Chen, Chenhui,Lu, Zhan
supporting information, p. 837 - 841 (2020/01/31)
An efficient cobalt-catalyzed migrational isomerization of styrenes was developed using the thiazoline iminopyridine (TIP) ligand. This reaction is operationally simple and atom-economical using readily available starting materials to access trisubstituted alkenes. Even when using a 0.1 mol % catalyst loading, the reaction could be conducted in neat and completed in 1 h with excellent conversion and high E stereoselectivity.
Preparation of Functionalized Diaryl- and Diheteroaryllanthanum Reagents by Fast Halogen–Lanthanum Exchange
Benischke, Andreas D.,Anthore-Dalion, Lucile,Berionni, Guillaume,Knochel, Paul
, p. 16390 - 16394 (2017/11/28)
Aryl and heteroaryl halides (X=Br, I) undergo a fast and convenient halogen–lanthanum exchange with nBu2LaMe, which leads to functionalized diaryl- and diheteroaryllanthanum derivatives. Subsequent trapping reactions with selected electrophiles, such as ketones, aldehydes, or amides, proceeded smoothly at ?50 °C in THF, affording polyfunctionalized alcohols and carbonyl derivatives. Kinetic competition experiments revealed a similar reactivity trend as for Br/Mg exchange, but 106-times higher rates, making it comparable to Br/Li exchange.
Rational Design, Synthesis, and Biological Evaluation of Heterocyclic Quinolones Targeting the Respiratory Chain of Mycobacterium tuberculosis
Hong, W. David,Gibbons, Peter D.,Leung, Suet C.,Amewu, Richard,Stocks, Paul A.,Stachulski, Andrew,Horta, Pedro,Cristiano, Maria L. S.,Shone, Alison E.,Moss, Darren,Ardrey, Alison,Sharma, Raman,Warman, Ashley J.,Bedingfield, Paul T. P.,Fisher, Nicholas E.,Aljayyoussi, Ghaith,Mead, Sally,Caws, Maxine,Berry, Neil G.,Ward, Stephen A.,Biagini, Giancarlo A.,O’Neill, Paul M.,Nixon, Gemma L.
supporting information, p. 3703 - 3726 (2017/05/19)
A high-throughput screen (HTS) was undertaken against the respiratory chain dehydrogenase component, NADH:menaquinone oxidoreductase (Ndh) of Mycobacterium tuberculosis (Mtb). The 11000 compounds were selected for the HTS based on the known phenothiazine Ndh inhibitors, trifluoperazine and thioridazine. Combined HTS (11000 compounds) and in-house screening of a limited number of quinolones (50 compounds) identified ～100 hits and four distinct chemotypes, the most promising of which contained the quinolone core. Subsequent Mtb screening of the complete in-house quinolone library (350 compounds) identified a further ～90 hits across three quinolone subtemplates. Quinolones containing the amine-based side chain were selected as the pharmacophore for further modification, resulting in metabolically stable quinolones effective against multi drug resistant (MDR) Mtb. The lead compound, 42a (MTC420), displays acceptable antituberculosis activity (Mtb IC50 = 525 nM, Mtb Wayne IC50 = 76 nM, and MDR Mtb patient isolates IC50 = 140 nM) and favorable pharmacokinetic and toxicological profiles.
Metal-Free Intermolecular Coupling of Arenes with Secondary Amides: Chemoselective Synthesis of Aromatic Ketimines and Ketones, and N-Deacylation of Secondary Amides
Huang, Pei-Qiang,Huang, Ying-Hong,Xiao, Kai-Jiong
, p. 9020 - 9027 (2016/10/17)
The direct transformation of common secondary amides into aromatic ketimines and aromatic ketones with C-C bond formation is described. The reaction can also be used for N-deacylation of secondary amides to release amines. This method consists of in situ amide activation with triflic anhydride and intermolecular capture of the resulting highly electrophilic nitrilium intermediate with an arene. The reaction is applicable to various kinds of secondary amides (electrophiles), but only electron-rich and moderately electron-rich arenes can be used as nucleophiles. Thanks to the use of bench stable arenes instead of reactive and basic organometallics as nucleophiles, the reaction proceeded with high chemoselectivity at the secondary amido group in the presence of a series of sensitive functional groups such as aldehyde, ketone, ester, cyano, nitro, and tertiary amido groups. The reaction can be viewed as a Friedel-Crafts-type reaction using secondary amides as acylating agents or as an intermolecular version of the Bischler-Napieralski reaction.
Tethered η5-oxocyclohexadienyl piano-stool ruthenium(II) complexes: A new class of catalysts?
Kechaou-Perrot, Manel,Vendier, Laure,Bastin, Stphanie,Sotiropoulos, Jean-Marc,Miqueu, Karinne,Menndez-Rodrguez, Luca,Crochet, Pascale,Cadierno, Victorio,Igau, Alain
supporting information, p. 6294 - 6297 (2015/02/19)
The straightforward synthesis of tethered η5-oxocyclohexadienyl Ru(II) complexes is presented. Pioneering results in catalysis show that these original half-sandwich Ru(II) complexes allow the effective isomerization of allylic alcohols under mild conditions without further additives; η5-oxocyclohexadienyl ruthenium complexes may be considered as a new class of catalysts.
Rhodium-catalyzed ketone methylation using methanol under mild conditions: Formation of α-branched products
Chan, Louis K. M.,Poole, Darren L.,Shen, Di,Healy, Mark P.,Donohoe, Timothy J.
supporting information, p. 761 - 765 (2014/01/23)
The rhodium-catalyzed methylation of ketones has been accomplished using methanol as the methylating agent and the hydrogen-borrowing method. The sequence is notable for the relatively low temperatures that are required and for the ability of the reaction system to form α-branched products with ease. Doubly alkylated ketones can be prepared from methyl ketones and two different alcohols by using a sequential one-pot iridium- and rhodium-catalyzed process. Uniquely effective for making branched alkyl products from ketones (see scheme): The scope of the presented reaction includes aromatic and aliphatic ketones and consecutive one-pot double alkylation reactions to provide a convenient route to branched ketones from simple methyl ketones. A brief study into the mechanism of the reaction has given evidence for an aldol-based reaction pathway.
Chemoselective synthesis of ketones and ketimines by addition of organometallic reagents to secondary amides
Bechara, William S.,Pelletier, Guillaume,Charette, Andre B.
experimental part, p. 228 - 234 (2012/06/01)
The development of efficient and selective transformations is crucial in synthetic chemistry as it opens new possibilities in the total synthesis of complex molecules. Applying such reactions to the synthesis of ketones is of great importance, as this motif serves as a synthetic handle for the elaboration of numerous organic functionalities. In this context, we report a general and chemoselective method based on an activation/addition sequence on secondary amides allowing the controlled isolation of structurally diverse ketones and ketimines. The generation of a highly electrophilic imidoyl triflate intermediate was found to be pivotal in the observed exceptional functional group tolerance, allowing the facile addition of readily available Grignard and diorganozinc reagents to amides, and avoiding commonly observed over-addition or reduction side reactions. The methodology has been applied to the formal synthesis of analogues of the antineoplastic agent Bexarotene and to the rapid and efficient synthesis of unsymmetrical diketones in a one-pot procedure. Macmillan Publishers Limited. All rights reserved.
Concise, convergent syntheses of (±)-trichostatin a utilizing a Pd-catalyzed ketone enolate α-alkenylation reaction
Cosner, Casey C.,Helquist, Paul
, p. 3564 - 3567 (2011/09/14)
Two concise, convergent syntheses of (±)-trichostatin A (1), a potent histone deacetylase inhibitor, have been accomplished. The key step in both is a Pd-catalyzed α-alkenylation reaction between ketone 2 and either dienyl bromide 3 or alkenyl bromide 9 u
Selective Oxidation of Benzylic and Allylic Alcohols Using Mn(OAc) 3/Catalytic 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
Cosner, Casey C.,Cabrera, Pablo J.,Byrd, Katherine M.,Adams Thomas, Asia M.,Helquist, Paul
supporting information; experimental part, p. 2071 - 2073 (2011/06/19)
A practical, chemoselective oxidation of alcohols employing catalytic quantities of DDQ as the oxidant and Mn(OAc)3 as the co-oxidant is described. Electron-rich benzylic alcohols are oxidized efficiently to their corresponding carbonyls, but less electron-rich benzylic alcohols remain unchanged. Allylic alcohols are rapidly oxidized to their corresponding aldehyde or ketone counterparts in high yields. This protocol is operationally simple, employs an inexpensive source of Mn(OAc)3, has short reaction times, and exhibits a significant chemoselectivity favoring allylic alcohols over benzylic alcohols. This procedure also avoids the use of very large excesses of reagents and sometimes poor reproducibility that characterize previously developed reagents such as MnO2
Highly water-soluble arene-ruthenium(ii) complexes: Application to catalytic isomerization of allylic alcohols in aqueous medium
Lastra-Barreira, Beatriz,Diez, Josefina,Crochet, Pascale
scheme or table, p. 1681 - 1686 (2010/06/20)
Arene-ruthenium(ii) derivatives [RuCl2(η6-C 6H5OCH2CH2OH)(L)] (L = P(OMe) 3 (2a), P(OEt)3 (2b), P(OiPr)3 (2c), P(OPh)3 (2d), PPh3 (2e)) have been prepared from the dimer [{RuCl(μ-Cl)(η6-C6H5OCH 2CH2OH)}2] and the appropriate P-donor ligand. The hydroxyethoxy substituent on the arene induces water-solubility of the resulting complexes (up to 755 g L-1); in particular derivative 2a being one hundred times more soluble in water than its p-cymene congener [RuCl2(η6-p-cymene){P(OMe)3}]. Compounds 2a-e are active catalysts for isomerization of allylic alcohols into the corresponding ketones in aqueous medium. The best performances are obtained with derivatives 2a-c which have shown the highest activity reported to date for the isomerization of aromatic or disubstituted substrates in water. The Royal Society of Chemistry 2009.
