Chiral and achiral pincer type palladium complexes bearing abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazole are reported. Both complexes are effective as catalysts for non-asymmetric Suzuki coupling reaction for the synthesis of biphenyl derivatives. However, both the complexes failed to catalyze the formation of binaphthyl derivatives, by the asymmetric Suzuki coupling in case of the chiral complex and the non-asymmetric version in case of the achiral pincer complex. Instead deboronation of arylboronic acid occurred very efficiently leaving the aryl bromide intact. © 2009 Elsevier Ltd. All rights reserved.

Sethuraman Sankararaman

Department Of Chemistry

Thandavamurthy Karthikeyan

1,2,3 TRIAZOLE DERIVATIVE

biphenyl derivative

boronic acid derivative

bromine derivative

carbenoid

naphthalene derivative

palladium complex

article

catalysis

reaction analysis

Suzuki reaction

synthesis

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IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Tetrahedron Letters

Synthesis of mononuclear and PEPPSI type palladium diiodo complexes of 1,4-diphenyl-3-methyl-1,2,3-triazol-5-ylidene without the use of strong bases and silver salts and at ambient conditions using Pd(OAc)2 is reported. Using stoichiometric amounts of bidendate ligands such as pyrazine, 4,4′-bipyridine and DABCO bridged binuclear palladium diiodo complexes were obtained in excellent yields. By simple variation of reagents and their stoichiometry, one can control the reactions towards the selective formation of mononuclear [(Tz)2Pd(I)2] complexes, iodo bridged binuclear complexes [(Tz)Pd(I)(μ-I)2Pd(I)(Tz)], mononuclear PEPPSI type complexes [(Tz)Pd(I)2(Py)], bridged binuclear PEPPSI type complexes [(Tz)Pd(I)2-(bridge biPy)-(I)2Pd(Tz)]. The catalytic activities of these three structurally different types of complexes are compared for Suzuki-Miyaura coupling reaction. © 2015 Elsevier B.V.

Journal of Organometallic Chemistry

A mild and efficient method for the synthesis of structurally diverse 1,2,3-triazolylidene palladium(II) diiodo complexes. Comparison of catalytic activities for Suzuki-Miyaura coupling

(-) Menthol was converted to 1-menthyl-3-methyl-4-phenyltriazolium iodide and 1-neomethyl-3-methyl-4-phenyltriazolium iodide in four steps. These triazolium salts that are enantio pure but diastereo isomers, served as precursors for the synthesis of the corresponding enantio pure bis(1,2,3-triazol-5-ylidene)PdI2 complexes with menthyl and neomenthyl wing tip groups. The palladium complexes were synthesized in high yields using a recently developed mild method under base free and silver free conditions at ambient temperature. These triazolium salts also served as precursors for the synthesis of the corresponding enantio pure PEPPSI type (1,2,3-triazol-5-ylidene) (pyridine)PdI2 complexes. All the complexes were thoroughly characterized by spectroscopic and single crystal XRD data. The relative catalytic activities of these complexes were compared for Suzuki-Miyaura C-C coupling. © 2015 Elsevier B.V. All rights reserved.

Synthesis and structures of (-) menthyl and (+) neomenthyl substituted enantio pure bis(1,2,3-triazol-5-ylidene)PdI2 complexes and PEPPSI type (1,2,3-triazol-5-ylidene) (pyridine)PdI2complexes. Comparison of catalytic activities for C-C coupling

Chiral 1,2,3-triazol-5-ylidene-Pd complexes with the planar chiral [2.2]paracyclophane wing tip group have been synthesized and structurally characterized. The complex with a labile acetonitrile co-ligand is an excellent catalyst for chemoselective hydrogenation of alkynes and alkenes and enantioselective hydrogenation of prochiral alkenes at ambient conditions and 1.0 atmosphere of H2. © 2015 The Royal Society of Chemistry.

RSC Advances

Catalytic asymmetric hydrogenation using a [2.2]paracyclophane based chiral 1,2,3-triazol-5-ylidene-Pd complex under ambient conditions and 1 atmosphere of H2

C2-Symmetric normal and mesoionic bis-N-heterocyclic carbenes (NHCs) derived from 1,1′-((1,1′-biphenyl)-2,2′- diylbis(methylene))bis(3-methyl-4-phenyl-1H-1,2,3-triazol-3-ium) diiodide (5) and 3,3′-((1,1′-biphenyl)-2,2′-diylbis(methylene))bis(1- phenyl-1H-imidazol-3-ium) dibromide (6) were used as ligands for the synthesis of the corresponding Pd(II) complexes. 2,2′-Disubstituted 1,1′-biphenyl moiety was used as the C2-symmetric backbone for the synthesis. 2,2′-Bis(bromomethyl)-1,1′-biphenyl was used as a common precursor for the synthesis of both 5 and 6. These salts were treated with Ag2O for the in-situ generation of the corresponding NHC-Ag(I) complexes which were transmetallated to the corresponding Pd(II) chloro and acetate complexes. The bis(1,2,3-triazol-5-ylidene) derivative gave structurally well-defined mono nuclear chelate complexes that were characterized by spectroscopic and single crystal XRD data. The bis(imidazol-3-ylidene) derivative gave polymeric complex and not the expected mono nuclear chelate complex. These complexes were compared for their reactivity in Suzuki-Miyaura coupling reaction. © 2014 Elsevier B.V. All rights reserved.

C2-Symmetric normal and mesoionic bis-N-heterocyclic carbenes with biphenyl backbone. A comparison of bis(1,2,3-triazol-5-ylidene) and bis(imidazol-2-ylidene) ligands

trans-Bis(1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene)palladium(II) dichloride has been shown to be an excellent catalyst for the multiple Suzuki-Miyaura coupling reactions of polybromoarenes to the corresponding fully substituted polyarylarenes. The reactions proceeded in excellent yields and with high turnover numbers. With 1,4-dibromobenzene the catalyst was found to be active for up to 13 consecutive cycles with a turnover number of 1260. The polyarylarenes were obtained in pure form after crystallization once without recourse to chromatographic purification. The single-crystal X-ray structures of the chloro (1) as well as the corresponding acetato (2) complexes are also reported and compared with the corresponding complexes of 1,4-diphenyl-3-methyl- 1,2,3-triazol-5-ylidene as the ligand. © 2013 Shaik et al.

Fulltext

Beilstein Journal of Organic Chemistry

Synthesis and structure of trans-bis(1,4-dimesityl-3-methyl-1,2,3-triazol- 5-ylidene)palladium(II) dichloride and diacetate. Suzuki-Miyaura coupling of polybromoarenes with high catalytic turnover efficiencies

The synthesis of new C2 symmetric bis(pyrrolidine-triazole)-based organocatalysts and their utility in the asymmetric Michael reaction of β-nitrostyrenes with very high diastereo- and enantioselectivity in water without any additives is reported. The asymmetric synthesis of nitrochromenes is also illustrated. © 2008 Elsevier Ltd. All rights reserved.

Tetrahedron Asymmetry

New pyrrolidine-triazole-based C2 symmetric organocatalysts and their utility in the asymmetric Michael reaction of β-nitrostyrenes and the synthesis of nitrochromenes

Benezit Dictionary of Artists

Albrecht, Albrecht

Chemical Reviews

Beyond ConventionalN-Heterocyclic Carbenes: Abnormal, Remote, and Other Classes of NHC Ligands with Reduced Heteroatom Stabilization

Accounts of Chemical Research

Surveying Sterically Demanding N-Heterocyclic Carbene Ligands with Restricted Flexibility for Palladium-catalyzed Cross-Coupling Reactions

Well-Defined N-Heterocyclic Carbenes−Palladium(II) Precatalysts for Cross-Coupling Reactions

Palladium complexes with abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazolium ions and their application in Suzuki coupling

Journal	Tetrahedron Letters
ISSN	00404039
Open Access	No