- Cross coupling of benzylammonium salts with boronic acids using a well-defined N-heterocyclic carbene-palladium(ii) precatalyst
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N-heterocyclic carbene-palladium(ii)-catalyzed cross-coupling of benzylammonium salts with arylboronic acids for the synthesis of diarylmethane derivatives via C-N bond activation has been developed. Notably, in the presence of the easily prepared and bench-stable Pd-PEPPSI precatalyst, the Csp3-N bond activation of the benzylammonium salt even proceeded smoothly in isopropanol at room temperature.
- Wang, Tao,Guo, Jiarui,Wang, Xiaojuan,Guo, Han,Jia, Dingli,Wang, Hengjin,Liu, Lantao
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- Dual copper- and photoredox-catalysed C(sp2)-C(sp3) coupling
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The use of copper catalysis with visible light photoredox catalysis in a cooperative fashion has recently emerged as a versatile means of developing new C-C bond forming reactions. In this work, dual copper and photoredox catalysis is exploited to effect C(sp2)-C(sp3) cross-couplings between aryl boronic acids and benzyl bromides.
- McLean, Euan B.,Gauchot, Vincent,Brunen, Sebastian,Burns, David J.,Lee, Ai-Lan
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supporting information
p. 4238 - 4241
(2019/04/30)
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- An Efficient Ga(OTf)3/Isopropanol Catalytic System for Direct Reduction of Benzylic Alcohols
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This study aims to report the first gallium-catalyzed direct reduction of benzylic alcohols using isopropanol as a reductant. The reaction proceeds via gallium catalyst-assisted hydride transfer of the in situ-generated benzylic isopropyl ether. The method generates only water and acetone as byproducts and thus provides an atom-economic and environmentally friendly approach to the synthesis of di- and triarylmethanes, which are important substructures in various bioactive compounds and functional materials. (Figure presented.).
- Sai, Masahiro
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p. 4330 - 4335
(2018/10/15)
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- Decarboxylative Benzylation of Aryl and Alkenyl Boronic Esters
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The copper-catalyzed decarboxylative benzylation of aryl and alkenyl boronic esters with electron-deficient aryl acetates is reported. The oxidative coupling proceeds under mild, aerobic conditions and tolerates a host of potentially reactive electrophilic functional groups that would be problematic with traditional benzylation methods (aryl iodides and bromides, protic heteroatoms, aldehydes, Michael acceptors). A reaction pathway in which a benzylic nucleophile is generated by aryl acetate decarboxylation and in turn is intercepted by the catalyst to form diarylmethane products is supported by mechanistic studies.
- Moon, Patrick J.,Fahandej-Sadi, Anis,Qian, Wenyu,Lundgren, Rylan J.
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p. 4612 - 4616
(2018/03/26)
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- Picolinamide modified β-cyclodextrin/Pd (II) complex: Asupramolecular catalyst for Suzuki-Miyaura coupling of aryl, benzyl and allyl halides with arylboronic acids in water
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Novel supramolecular catalysts for Suzuki-Miyaura coupling were prepared and characterized by NMR, FT-IR, TEM, XRD, TGA, and XPS. The resulting picolinamide-modified β-cyclodextrin/Pd(II) complex (Pd(II)@PCA-β-CD) showed very efficient catalytic activity for Suzuki-Miyaura coupling of aryl, benzyl, and allyl halides with arylboronic acids in an environmentally benign aqueous solution. Various organic halides including chlorides can produce good to excellent yields with phenyl-boronic acid and a catalytic amount of Pd(II)@PCA-β-CD. This hydro-soluble catalyst was capable of being reused for at least eight runs with only a slight loss of catalytic activity. A putative mechanism of the Pd(II)/Pd(IV) catalytic cycle was also explored and calculated by ab initio QM/MM methods.
- Luo, Kaixiu,Zhang, Lu,Yang, Rui,Jin, Yi,Lin, Jun
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p. 200 - 210
(2018/08/09)
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- Design, Synthesis, and Evaluation of Thyronamine Analogues as Novel Potent Mouse Trace Amine Associated Receptor 1 (m TAAR1) Agonists
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Trace amine associated receptor 1 (TAAR1) is a G protein coupled receptor (GPCR) expressed in brain and periphery activated by a wide spectrum of agonists that include, but are not limited to, trace amines (TAs), amphetamine-like psychostimulants, and end
- Chiellini, Grazia,Nesi, Giulia,Digiacomo, Maria,Malvasi, Rossella,Espinoza, Stefano,Sabatini, Martina,Frascarelli, Sabina,Laurino, Annunziatina,Cichero, Elena,Macchia, Marco,Gainetdinov, Raul R.,Fossa, Paola,Raimondi, Laura,Zucchi, Riccardo,Rapposelli, Simona
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p. 5096 - 5107
(2015/07/02)
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- SYNTHETIC ANALOGUES OF 3-IODOTHYRONAMINE (T1AM) AND USES THEREOF
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Novel synthetic analogues of 3-iodothyronamine of formula (I), pharmaceutical compositions containing the same, and medical uses thereof are described.
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Page/Page column 5; 6
(2015/11/02)
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- One-pot synthesis of symmetrical and unsymmetrical diarylmethanes via diborylmethane
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A one-pot synthesis of diarylmethanes from air-stable diborylmethane via the Suzuki-Miyaura cross-coupling reaction is described. The present approach realizes the synthesis of various symmetrical and unsymmetrical diarylmethanes in good to excellent yields.
- Endo, Kohei,Ishioka, Takafumi,Ohkubo, Takahiro,Shibata, Takanori
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p. 7223 - 7231
(2012/10/29)
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- Synthesis of diarylmethane derivatives from Stille cross-coupling reactions of benzylic halides
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A catalyst precursor prepared in situ from palladium acetate and a phosphine ligand was used for the Stille cross-coupling reaction of benzylic bromides and chlorides with aryltributyltin analogues. The reactions were performed at 80 °C using dppf as ligand in the presence of KF, or more conveniently using PPh3 in the absence of base, furnishing diarylmethane derivatives in high yields (86-99%). Using Pd(OAc)2/PPh3 as catalyst precursor competitive Stille and Suzuki cross-coupling reactions with benzyl chloride showed that in the absence of base or in the presence of KF the Stille product is the majority product, and only the Suzuki product was obtained in the presence of KOH as base.
- Nichele, Tatiana Z.,Monteiro, Adriano L.
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p. 7472 - 7475
(2008/03/14)
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- Palladium catalyzed ligand-free Suzuki cross-coupling reactions of benzylic halides with aryl boronic acids under mild conditions
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A highly efficient Suzuki cross-coupling reaction between benzylic halides and aryl boronic acids using palladium chloride as catalyst in acetone:water (3:1) has been developed. High yields of products, mild reaction conditions and short reaction times in the absence of ligand are important features of this method. A highly efficient Suzuki cross-coupling reaction between benzylic halides and aryl boronic acids using palladium chloride as catalyst in acetone:water (3:1) as the solvent system has been developed. High yields of products, mild reaction conditions and short reaction times in the absence of ligand are important features of this method.
- Bandgar,Bettigeri, Sampada V.,Phopase, Jaywant
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p. 6959 - 6962
(2007/10/03)
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- Suzuki cross-coupling reaction of benzylic halides with arylboronic acids in the presence of a tetraphosphine/palladium catalyst
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The cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl) cyclopentane-[PdCl(C3H5)]2 system catalyses efficiently the Suzuki cross-coupling reaction of benzylic halides with arylboronic acids. A wide variety of benzylic bromides or chlorides and functionalised arylboronic acids lead selectively to the corresponding diarylmethane adducts in good yields. Furthermore, this catalyst can be used at low loading in many cases.
- Chahen, Ludovic,Doucet, Henri,Santelli, Maurice
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p. 1668 - 1672
(2007/10/03)
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- Environmentally friendly arylmethylation of aromatics with benzyl halides using envirocat EPZ10 as the catalyst
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The Friedel-Crafts arylmethylation of aromatics with benzyl halides or bis-(bromomethyl)-benzene in the presence of Envirocat EPZ10 affords selectively para-arylmethylated products in good yields. Isolation of pure products involving an eco-friendly procedure and recyclability of the catalyst are important features of this method.
- Bandgar, Babasaheb P.,Kasture, Suhas P.
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p. 913 - 915
(2007/10/03)
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- Electrophilic aromatic substitution. 12. Kinectic studies of the TiCl4-catalyzed reactions of benzyl chloride, p-xylyl chloride, and p-nitrobenzyl chlordie with benzene and anisole in nitromehtane and dichloromethabe
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Through the use of vacuum line techniques, noncompetitive and competitive kinetic data have been obtained for the TiCl4-catalyzed reactions of benzyl chloride and p-methyl- and p-nitrobenzyl chloride with anisole and with benzene in solvents ni
- DeHaan, Franklin P.,Chan, Wai H.,Chang, Jeffrey,Cheng, Terry B.,Chiriboga, Douglas A.,Irving, Mark M.,Kaufman, Craig R.,Kim, Gia Y.,Kumar, Amit,Na, Jim,Nguyen, Tien T.,Tim Nguyen,Patel, Bimal R.,Sarin, Neal P.,Tidwell, Jeffrey H.
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p. 356 - 363
(2007/10/02)
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- FRIEDEL-CRAFTS ALKYLATION OF ANISOLE AND ITS COMPARISON WITH TOLUENE. PREDOMINANT ORTHO-PARA SUBSTITUTION UNDER KINETIC CONDITIONS AND THE EFFECT OF THERMODYNAMIC ISOMERIZATIONS
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The AlCl3 and BF3, as well as 65percent HPF6, catalyzed Friedel-Crafts alkylation of anisole with alkyl halides and alkohols was investigated.The alkylation of anisole with lower catalyst concentrations under mild conditions shows predominant ortho/para directing effect generally with a ratio of c.a. 2:1, with the amount of meta isomer uniformly less than 3percent.With "swamping" catalyst conditions the amount of meta substitution in methylation and ethylation can substantially increase.The isomer distribution in tert-butylation changes with time due to rapid ortho-para interconversion.Consequently, the AlCl3-catalyzed isomerization of isomeric alkylanisoles was also studied.In case of tert-butylanisoles, the ortho isomer shows relatively rapid conversion into para followed by much slower isomerization to meta.The para and meta isomers show isomerization to meta-para mixtures.Isomerization of ethyl-, isopropyl-, and benzylanisoles is generally slow whereas methylanisoles do not isomerize.Comparing results of the alkylation of anisole with toluene leads to the conclusion that the latter are readily affected by concurrent (and in some cases consecutive) isomerization.As the barrier for isomerization in the benzenium ion intermediates of the alkylations is higher in the case of CH3O- than CH3-substituted systems, anisole tends to give the kinetically controlled ortho-para alkylation products and the amount of meta isomer is low.Study of alkylation of 3,5-di- and 2,4,6-trideuterated toluene and anisole and comparing retained deuterium contents with isomer distributions shows that alkylated product formation in case of toluene, but not of anisole, is proceeded by intramolecular, 1,2-alkyl, and hydrogen-deuterium shifting resulting also in increased meta substitution.This effect is most predominant in methylation and ethylation where the alkyl shifts are intramolecular but not in tert-butylation and benzylation, where alkyl transfer is intermolecular.Isopropylation is intermediate in nature.No simple selectivity-reactivity relationship is indicated in the studied alkylation reactions.As shown in benzylations with increasingly electron-donating and -withdrawing substituted benzyl chlorides overall rate (i.e., substrate selectivity) and isomer distributions (i.e., regioselectivity) are not determined in the same step as significantly decreased substrate selectivity is not accompanied by loss of positional selectivity.Previously reported alkylations showing high degree of meta substitution therefore, must have been affected by thermodynamically controlled rearrangement processes, including intramolecular alkyl and hydrogen shifts in the arenium ion intermediates of the alkylation reactions.These are to be differentiated from possible subsequent product isomerizations.Under predominantly kinetic conditions anisole as well as toluene are substantially ortho-para directing in alkylations, as in other electrophilic aromatic substitutions.
- Olah, George A.,Olah, Judith A.,Ohyama, Toshiyuki
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p. 5284 - 5290
(2007/10/02)
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- 4-NITROBENZYLATION OF PHENOL AND ANISOLE IN THE PRESENCE OF SMALL AMOUNTS OF FERRIC CHLORIDE
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Unlike other substituted benzylchlorides, 4-nitrobenzyl chloride enters into reaction with phenol and anisole in the presence of 1E-2 - 1E-3 mole of ferric chloride.The yields of the 4-nitrobenzylphenols (anisoles) amount to 64-80percent.It was shown that
- Tadzhimukhamedov, Kh. S.,Abdurasuleva, A. R.,Akhmedov, K. N.
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p. 944 - 946
(2007/10/02)
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