The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
H. Maheswaran - One of the best experts on this subject based on the ideXlab platform.
-
copper catalyzed ipso nitration of iodoarenes bromoarenes and heterocyclic Haloarenes under ligand free conditions
ChemInform, 2012Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:An excellent functional group tolerance and an extended substrate scope allow the synthesis of a broad spectrum of important nitroarene constituents under conditions A) or B) with complete regioselectivity.
-
copper catalyzed ipso nitration of iodoarenes bromoarenes and heterocyclic Haloarenes under ligand free conditions
Tetrahedron Letters, 2012Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:A catalytic protocol for the conversion of Haloarenes into the corresponding nitroarenes is presented using copper salts under ligand-free conditions. The method was effectively utilized for the ipso-nitration of a broad variety of Haloarenes that includes iodoarenes, bromoarenes, and heterocyclic Haloarenes.
-
sulfonic acid resin and copper salts a novel heterogeneous catalytic system for direct hydroxylation of Haloarenes
ChemInform, 2011Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:The corresponding phenols in excellent yields, a wide range of functional groups is tolerated.
-
sulfonic acid resin and copper salts a novel heterogeneous catalytic system for direct hydroxylation of Haloarenes
Catalysis Science & Technology, 2011Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:A sulfonic acid resin (INDION-770) in combination with Cu salts is demonstrated to be a versatile heterogeneous catalyst for direct hydroxylation of Haloarenes to give corresponding phenols in excellent yields.
-
sulfonic acid containing cation exchanger resin indion 770 and copper i salts a novel reusable catalyst for n arylation of nh heterocycles with Haloarenes
Catalysis Science & Technology, 2011Co-Authors: P Amal J Joseph, Shalini Priyadarshini, Lakshmi M Kantam, H. MaheswaranAbstract:Industrial grade sulfonic acid based cation-exchanger resin “INDION-770” in combination with Cu(I) salts is demonstrated to be a versatile heterogeneous catalytic system for direct N-arylation of NH-heterocycles with various Haloarenes to give the corresponding N-arylheterocycles in good to excellent yields.
Piotr Kaszynski - One of the best experts on this subject based on the ideXlab platform.
-
azo group assisted nucleophilic aromatic substitutions in Haloarene derivatives preparation of substituted 1 iodo 2 6 bispropylthiobenzenes
Journal of Organic Chemistry, 2004Co-Authors: Jason Manka, Virginia C Mckenzie, Piotr KaszynskiAbstract:Aryldiazo substituents were used in nucleophilic aromatic substitution reactions of halogens. The Ph-NN− group activates ortho fluorine atoms toward alkylthiolation under mild conditions. In contra...
-
azo group assisted nucleophilic aromatic substitutions in Haloarene derivatives preparation of substituted 1 iodo 2 6 bispropylthiobenzenes
Journal of Organic Chemistry, 2004Co-Authors: Jason Manka, Virginia C Mckenzie, Piotr KaszynskiAbstract:Aryldiazo substituents were used in nucleophilic aromatic substitution reactions of halogens. The Ph-NN− group activates ortho fluorine atoms toward alkylthiolation under mild conditions. In contrast, the Me2N-C6H4-NN− group has virtually no activation effect in nucleophilic aromatic substitution, and serves as a “neutral” mask for the amino group. The Ph-NN− group was efficiently introduced by diazo coupling of aryllithium with dry PhN2+BF4- salt.
P Amal J Joseph - One of the best experts on this subject based on the ideXlab platform.
-
copper catalyzed ipso nitration of iodoarenes bromoarenes and heterocyclic Haloarenes under ligand free conditions
ChemInform, 2012Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:An excellent functional group tolerance and an extended substrate scope allow the synthesis of a broad spectrum of important nitroarene constituents under conditions A) or B) with complete regioselectivity.
-
copper catalyzed ipso nitration of iodoarenes bromoarenes and heterocyclic Haloarenes under ligand free conditions
Tetrahedron Letters, 2012Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:A catalytic protocol for the conversion of Haloarenes into the corresponding nitroarenes is presented using copper salts under ligand-free conditions. The method was effectively utilized for the ipso-nitration of a broad variety of Haloarenes that includes iodoarenes, bromoarenes, and heterocyclic Haloarenes.
-
sulfonic acid resin and copper salts a novel heterogeneous catalytic system for direct hydroxylation of Haloarenes
ChemInform, 2011Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:The corresponding phenols in excellent yields, a wide range of functional groups is tolerated.
-
sulfonic acid resin and copper salts a novel heterogeneous catalytic system for direct hydroxylation of Haloarenes
Catalysis Science & Technology, 2011Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:A sulfonic acid resin (INDION-770) in combination with Cu salts is demonstrated to be a versatile heterogeneous catalyst for direct hydroxylation of Haloarenes to give corresponding phenols in excellent yields.
-
sulfonic acid containing cation exchanger resin indion 770 and copper i salts a novel reusable catalyst for n arylation of nh heterocycles with Haloarenes
Catalysis Science & Technology, 2011Co-Authors: P Amal J Joseph, Shalini Priyadarshini, Lakshmi M Kantam, H. MaheswaranAbstract:Industrial grade sulfonic acid based cation-exchanger resin “INDION-770” in combination with Cu(I) salts is demonstrated to be a versatile heterogeneous catalytic system for direct N-arylation of NH-heterocycles with various Haloarenes to give the corresponding N-arylheterocycles in good to excellent yields.
Lakshmi M Kantam - One of the best experts on this subject based on the ideXlab platform.
-
copper catalyzed ipso nitration of iodoarenes bromoarenes and heterocyclic Haloarenes under ligand free conditions
ChemInform, 2012Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:An excellent functional group tolerance and an extended substrate scope allow the synthesis of a broad spectrum of important nitroarene constituents under conditions A) or B) with complete regioselectivity.
-
copper catalyzed ipso nitration of iodoarenes bromoarenes and heterocyclic Haloarenes under ligand free conditions
Tetrahedron Letters, 2012Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:A catalytic protocol for the conversion of Haloarenes into the corresponding nitroarenes is presented using copper salts under ligand-free conditions. The method was effectively utilized for the ipso-nitration of a broad variety of Haloarenes that includes iodoarenes, bromoarenes, and heterocyclic Haloarenes.
-
sulfonic acid resin and copper salts a novel heterogeneous catalytic system for direct hydroxylation of Haloarenes
ChemInform, 2011Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:The corresponding phenols in excellent yields, a wide range of functional groups is tolerated.
-
sulfonic acid resin and copper salts a novel heterogeneous catalytic system for direct hydroxylation of Haloarenes
Catalysis Science & Technology, 2011Co-Authors: P Amal J Joseph, Lakshmi M Kantam, S Priyadarshini, H. MaheswaranAbstract:A sulfonic acid resin (INDION-770) in combination with Cu salts is demonstrated to be a versatile heterogeneous catalyst for direct hydroxylation of Haloarenes to give corresponding phenols in excellent yields.
-
sulfonic acid containing cation exchanger resin indion 770 and copper i salts a novel reusable catalyst for n arylation of nh heterocycles with Haloarenes
Catalysis Science & Technology, 2011Co-Authors: P Amal J Joseph, Shalini Priyadarshini, Lakshmi M Kantam, H. MaheswaranAbstract:Industrial grade sulfonic acid based cation-exchanger resin “INDION-770” in combination with Cu(I) salts is demonstrated to be a versatile heterogeneous catalytic system for direct N-arylation of NH-heterocycles with various Haloarenes to give the corresponding N-arylheterocycles in good to excellent yields.
John A Murphy - One of the best experts on this subject based on the ideXlab platform.
-
dual roles for potassium hydride in Haloarene reduction csnar and single electron transfer reduction via organic electron donors formed in benzene
Journal of the American Chemical Society, 2018Co-Authors: Joshua P Barham, Samuel E Dalton, Mark Allison, Giuseppe Nocera, Allan Young, Matthew P John, Thomas M Mcguire, Sebastien Andre Campos, Tell Tuttle, John A MurphyAbstract:Potassium hydride behaves uniquely and differently than sodium hydride toward aryl halides. Its reactions with a range of Haloarenes, including designed 2,6-dialkylHaloarenes, were studied in THF and in benzene. In THF, evidence supports concerted nucleophilic aromatic substitution, CSNAr, and the mechanism originally proposed by Pierre et al. is now validated through DFT studies. In benzene, besides this pathway, strong evidence for single electron transfer chemistry is reported. Experimental observations and DFT studies lead us to propose organic super electron donor generation to initiate BHAS (base-promoted homolytic aromatic substitution) cycles. Organic donor formation originates from deprotonation of benzene by KH; attack on benzene by the resulting phenylpotassium generates phenylcyclohexadienylpotassium that can undergo (i) deprotonation to form an organic super electron donor or (ii) hydride loss to afford biphenyl. Until now, BHAS reactions have been triggered by reaction of a base, MOtBu (M = ...
-
Dual Roles for Potassium Hydride in Haloarene Reduction: CSNAr and Single Electron Transfer Reduction via Organic Electron Donors Formed in Benzene
2018Co-Authors: Joshua P. Barham, Samuel E Dalton, Mark Allison, Giuseppe Nocera, Allan Young, Matthew P John, Tell Tuttle, Thomas Mcguire, Sebastien Campos, John A MurphyAbstract:Potassium hydride behaves uniquely and differently than sodium hydride toward aryl halides. Its reactions with a range of Haloarenes, including designed 2,6-dialkylHaloarenes, were studied in THF and in benzene. In THF, evidence supports concerted nucleophilic aromatic substitution, CSNAr, and the mechanism originally proposed by Pierre et al. is now validated through DFT studies. In benzene, besides this pathway, strong evidence for single electron transfer chemistry is reported. Experimental observations and DFT studies lead us to propose organic super electron donor generation to initiate BHAS (base-promoted homolytic aromatic substitution) cycles. Organic donor formation originates from deprotonation of benzene by KH; attack on benzene by the resulting phenylpotassium generates phenylcyclohexadienylpotassium that can undergo (i) deprotonation to form an organic super electron donor or (ii) hydride loss to afford biphenyl. Until now, BHAS reactions have been triggered by reaction of a base, MOtBu (M = K, Na), with many different types of organic additive, all containing heteroatoms (N or O or S) that enhance their acidity and place them within range of MOtBu as a base. This paper shows that with the stronger base, KH, even a hydrocarbon (benzene) can be converted into an electron-donating initiator
-
Discovery and Development of Organic Super-Electron-Donors
2016Co-Authors: John A MurphyAbstract:ABSTRACT: Based on simple ideas of electron-rich alkenes, exemplified by tetrakis(dimethylamino)ethene, TDAE, and on additional driving force associated with aromatization, families of very powerful neutral organic super-electron-donors (SEDs) have been developed. In the ground state, they carry out metal-free reductions of a range of functional groups. Iodoarenes are reduced either to aryl radicals or, with stronger donors, to aryl anions. Reduction to aryl radicals allows the initiation of very efficient transition-metal-free coupling of Haloarenes to arenes. The donors also reduce alkyl halides, arenesulfonamides, triflates, and triflamdes, Weinreb amides, and acyloin derivatives. Under photoactivation at 365 nm, they are even more powerful and reductively cleave aryl chlorides. They reduce unactivated benzenes to the corresponding radical anions and display original selectivities in preferentially reducing benzenes over malonates or cyanoacetates. Additionally, they reductively cleave ArC−X, ArX−C (X = N or O) and ArC−C bonds, provided that the two resulting fragments are somewhat stabilized. Recently, families of highly reactive organic reducing agents,the “super-electron-donors”, have been discovered and developed, based on very simple molecular design.1 This Perspective charts their emergence, their preparation, and their applications to date. In line with the personal nature of Perspectives, the article surveys the particular role that my research group has enjoyed in these developments. Aside fro
-
double deprotonation of pyridinols generates potent organic electron donor initiators for Haloarene arene coupling
Angewandte Chemie, 2016Co-Authors: Joshua P Barham, Matthew P John, Graeme Coulthard, Ryan G Kane, Nathan Delgado, John A MurphyAbstract:Transition metal-free couplings of Haloarenes with arenes, triggered by the use of alkali metal alkoxides in the presence of an organic additive, are receiving significant attention in the literature. Most of the known organic additives effect coupling of iodoarenes, but not bromoarenes, to arenes. Recently it was reported that 2-pyridinecarbinol (11) extends the reaction to aryl bromides. This paper investigates the mechanism, and reports evidence for dianions derived from 11 as electron donors to initiate the reaction. It also proposes routes by which electron-poor benzoyl derivatives can be transformed into electron donors to initiate these reactions.
-
organic super electron donors initiators in transition metal free Haloarene arene coupling
Chemical Science, 2014Co-Authors: Shengze Zhou, Tell Tuttle, Greg M Anderson, Bhaskar Mondal, Eswararao Doni, Vicki Ironmonger, Michael Kranz, John A MurphyAbstract:Recent papers report transition metal-free couplings of Haloarenes to arenes to form biaryls, triggered by alkali metal tert-butoxides in the presence of various additives. These reactions proceed through radical intermediates, but understanding the origin of the radicals has been problematic. Electron transfer from a complex formed from potassium tert-butoxide with additives, such as phenanthroline, has been suggested to initiate the radical process. However, our computational results encouraged us to search for alternatives. We report that heterocycle-derived organic electron donors achieve the coupling reactions and these donors can form in situ in the above cases. We show that an electron transfer route can operate either with phenanthrolines as additives or using pyridine as solvent, and we propose new heterocyclic structures for the respective electron donors involved in these cases. In the absence of additives, the coupling reactions are still successful, although more sluggish, and in those cases benzynes are proposed to play crucial roles in the initiation process.
