7022-45-9Relevant academic research and scientific papers
Rhodium(III)-Catalyzed Aldehyde C?H Activation and Functionalization with Dioxazolones: An Entry to Imide Synthesis
Bellière-Baca, Virginie,Clavier, Hervé,Hérault, Damien,Massouh, Joe,Petrelli, Antoine
supporting information, (2022/01/06)
A rhodium(III)-based catalytic system has been used to develop a C?H bond activation of benzaldehyde derivatives and subsequent functionalization with dioxazolones in order to afford imides. The importance of the nature of the directing group to perform selectively the aldehydic C?H bond activation has been highlighted. The scope investigation showed that this transformation could be applied to various dioxazolones and many benzaldehyde derivatives as well as an acrolein derivative. Derivatization reactions of the imide products demonstrated the synthetic utility of this rhodium-catalyzed aldehydic C?H amidation.
Nickel-Catalyzed Inter- and Intramolecular Aryl Thioether Metathesis by Reversible Arylation
Delcaillau, Tristan,Bismuto, Alessandro,Lian, Zhong,Morandi, Bill
supporting information, p. 2110 - 2114 (2019/12/24)
A nickel-catalyzed aryl thioether metathesis has been developed to access high-value thioethers. 1,2-Bis(dicyclohexylphosphino)ethane (dcype) is essential to promote this highly functional-group-tolerant reaction. Furthermore, synthetically challenging macrocycles could be obtained in good yield in an unusual example of ring-closing metathesis that does not involve alkene bonds. In-depth organometallic studies support a reversible Ni0/NiII pathway to product formation. Overall, this work not only provides a more sustainable alternative to previous catalytic systems based on Pd, but also presents new applications and mechanistic information that are highly relevant to the further development and application of unusual single-bond metathesis reactions.
Unexpected formation of 4,7-dihalobenzo[b]thiophenes using Ohira-Bestmann reagent and reactivity of the halogen-substituted benzo[b]thiophenes in Suzuki-Miyaura coupling with phenylboronic acid
Toyota, Kozo,Mutoh, Hirotaka,Kishi, Hiroki,Mikami, Shinichi,Tanaka, Hiroki,Yoshida, Shuhei,Naganuma, Daisuke
, p. 1355 - 1374 (2019/12/23)
Reaction of 2-(1-adamantylsulfanyl)-3,6-dihalobenzaldehydes with Ohira-Bestmann reagent gave 4,7-dihalobenzo[b]thiophenes along with normal alkyne products. Nine types of 4,7-dihalobenzo[b]thiophenes bearing chlorine, bromine, or iodine atoms, were prepared by this method. Regioselectivity in Suzuki-Miyaura cross coupling reactions of the 4,7-dihalobenzo[b]thiophenes with PhB(OH)2 was also studied.
Construction of highly functionalized thiophene and benzo[b]thiophene derivatives via a sequence of propargyl–allenyl isomerization/cyclization/demethylation
Chen, Dianpeng,Xing, Gangdong,Chen, Xueyuan,Yao, Jinzhong,Zhou, Hongwei
supporting information, p. 5124 - 5126 (2016/11/09)
An efficient one-pot protocol for the synthesis of functionalized thiophene and benzo[b]thiophene derivatives was developed via a sequence of propargyl–allenyl isomerization/cyclization/demethylation. As a result of the readily accessible starting materials, simple operation, and mild conditions, this reaction should have potential utility in organic synthesis.
A convenient method for the synthesis of aryl methyl sulfides via Cu(I)-mediated methylthiolation of haloarenes with DMSO
Ghosh, Ketaki,Ranjit, Sadananda,Mal, Dipakranjan
supporting information, p. 5199 - 5202 (2015/08/19)
An efficient process for the Cu(I)-mediated methylthiolation of haloarenes using simple and readily available DMSO as a convenient and environment friendly source of SMe moiety has been developed. In the presence of CuI and DABCO, a variety of aryl/heteroaryl halides reacted with DMSO to afford corresponding aryl methyl sulfides in good to excellent yields.
The Key Role of the Nonchelating Conformation of the Benzylidene Ligand on the Formation and Initiation of Hoveyda-Grubbs Metathesis Catalysts
Bieszczad, Bartosz,Barbasiewicz, Micha?
supporting information, p. 10322 - 10325 (2015/07/07)
Experimental studies of Hoveyda-Grubbs metathesis catalysts reveal important consequences of substitution at the 6-position of the chelating benzylidene ligand. The structural modification varies conformational preferences of the ligand that affects its exchange due to the interaction of the coordinating site with the ruthenium center. As a consequence, when typical S-chelated systems are formed as kinetic trans-Cl2 products, for 6-substituted benzylidenes the preference is altered toward direct formation of thermodynamic cis-Cl2 isomers. Activity data and reactions with tricyclohexylphosphine (PCy3) support also a similar scenario for O-chelated complexes, which display fast trans-Cl2?cis-Cl2 equilibrium observed by NMR EXSY studies. The presented conformational model reveals that catalysts, which cannot adopt the optimal nonchelating conformation of benzylidene ligand, initiate through a high-energy associative mechanism.
SULFUR CHELATED RUTHENIUM COMPOUNDS USEFUL AS OLEFIN METATHESIS CATALYSTS
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Paragraph 0058, (2014/06/23)
Sulfur chelated ruthenium compounds represented by the following formula: wherein M indicates the ruthenium metal bound to a benzylidene carbon; R represents C1-C7 alkyl group or optionally substituted aryl; X1 and X2 each independently represent halogen; Y1 and Y2 each independently denote unsubstituted or alkyl-substituted phenyl; and Z independently represents hydrogen, electron withdrawing or electron donating substituent, with m being an integer from 1 to 4, and processes and compositions related thereto.
Aryl methyl sulfides via SNAr using DMSO as the source of the thiomethyl moiety
Jones-Mensah, Ebenezer,Magolan, Jakob
supporting information, p. 5323 - 5326 (2015/01/16)
A unique synthesis of aryl methyl sulfides is reported proceeding via reduction of dimethylsulfoxide to dimethylsulfide at elevated temperature in the presence of Hunig's base followed by nucleophilic aromatic substitution and demethylation. Activated aryl fluorides, chlorides, and nitrobenzenes are suitable substrates with 13 examples provided. Dimethylsulfoxide serves as a simple and inexpensive formal source of the thiomethyl moiety.
Intermolecular alkyne hydroacylation. mechanistic insight from the isolation of the vinyl intermediate that precedes reductive elimination
Pawley, Rebekah J.,Huertos, Miguel A.,Lloyd-Jones, Guy C.,Weller, Andrew S.,Willis, Michael C.
, p. 5650 - 5659 (2012/11/14)
The isolation of the branched alkenyl intermediate that directly precedes reductive elimination of the final α,β-unsaturated ketone product is reported for the hydroacylation reaction between the alkyne HC≡CAr F (ArF = 3,5-(CF3)2C 6H3) and the β-S-substituted aldehyde 2-(methylthio)benzaldehyde: [Rh(fac-κ3-DPEphos)(C(=CH 2)ArF)(C(O)C6H4SMe) 2][CB11H12]. The structure of this intermediate shows that, in this system at least, hydride migration rather than acyl migration occurs. Kinetic studies on the subsequent reductive elimination to form the crystallographically characterized ketone-bound product [Rh(cis-κ2-DPEphos)(η2:η2, κ1-H2C=C(ArF)C(=O)(C6H 4SMe)][CB11H12] yield the following activation parameters for reductive elimination, which follows first-order kinetics (k obs = (6.14 ± 0.04) × 10-5 s-1, 324 K): ΔH = 95 ± 2 kJ mol-1, ΔS = -32 ± 7 J K-1 mol-1, ΔG(298 K) = 105 ± 4 kJ mol-1. Mechanistic studies, including selective deuteration experiments, show that hydride insertion is not reversible and also reveal that an interesting isomerization process is occurring between the two branched alkenyl protons that is suggested to occur via a metallocyclopropene intermediate. During catalysis, the consumption of substrates and evolution of products follow pseudo zero-order kinetics. The observation of both linear and branched products under stoichiometric and catalytic regimes, in combination with kinetic modeling, allows for an overall mechanistic scheme to be presented. Partitioning of linear and branched pathways at the hydride insertion step occurs with an approximate 2:1 selectivity, while reductive elimination of the linear product is at least 3 orders of magnitude faster than that from the branched. An explanation for the large difference in rate of reductive elimination in this system, as recently outlined by Goldman, Krogh-Jespersen, and Brookhart, is that steric crowding in branched intermediates can slow C-C reductive elimination even though such species are higher in energy than their linear analogues, if the rotation of the vinyl group to the appropriate orientation is inhibited by steric crowding in the branched isomers.
Studies on electronic effects in O-, N- and S-chelated ruthenium olefin-metathesis catalysts
Tzur, Eyal,Szadkowska, Anna,Ben-Asuly, Amos,Makal, Anna,Goldberg, Israel,Wozniak, Krzysztof,Grela, Karol,Lemcoff, N. Gabriel
experimental part, p. 8726 - 8737 (2010/10/19)
A short overview on the structural design of the Hoveyda-Grubbs-type ruthenium initiators chelated through oxygen, nitrogen or sulfur atoms is presented. Our aim was to compare and contrast O-, N- and S-chelated ruthenium complexes to better understand the impact of electron-withdrawing and -donating substituents on the geometry and activity of the ruthenium complexes and to gain further insight into the trans-cis isomerisation process of the S-chelated complexes. To evaluate the different effects of chelating heteroatoms and to probe electronic effects on sulfur- and nitrogen-chelated latent catalysts, we synthesised a series of novel complexes. These catalysts were compared against two well-known oxygen-chelated initiators and a sulfoxide-chelated complex. The structures of the new complexes have been determined by single-crystal X-ray diffraction and analysed to search for correlations between the structural features and activity. The replacement of the oxygen-chelating atom by a sulfur or nitrogen atom resulted in catalysts that were inert at room temperature for typical ring-closing metathesis (RCM) and cross-metathesis reactions and showed catalytic activity only at higher temperatures. Furthermore, one nitrogen-chelated initiator demonstrated thermo-switchable behaviour in RCM reactions, similar to its sulfur-chelated counterparts.
