Phosphine Ligand-Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions

Bin Guo, Tian Qi Yu, Hong Xi Li, Shi Qi Zhang, Pierre Braunstein, David J. Young, Hai Yan Li, Jian Ping Lang

Research output: Contribution to journalArticleResearchpeer-review

Abstract

A series of phosphine-free Ru(III)/Ru(II) complexes of NH functionalized N ˄ N ˄ N pincer ligands exhibit excellent activity for acceptorless dehydrogenative coupling (ADC) of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. Ru(III) complexes [LRuCl 3 ] (L=6-(3-R 1 ,5-R 2 -1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2-amine; 1 a: R 1 =R 2 =H (L1); 1 b: R 1 =R 2 =Me (L2); 1 c: R 1 =H, R 2 =CF 3 (L3); 1 d: R 1 =H, R 2 =Ph (L4); 1b Me : L=6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-methyl-N-(pyridin-2-yl)pyridin-2-amine (L2 Me )) were obtained by refluxing RuCl 3 ⋅ xH 2 O with the corresponding ligand in EtOH. Five Ru(II) complexes [LRu(DMSO-κS)Cl 2 ] (2 a: L=L1; 2 b: L=L2; 2 c: L=L3; 2 d: L=L4; 2b Me : L=L2 Me ) were formed by reducing the corresponding Ru(III) complex in refluxing EtOH. The latter complexes could also be prepared directly by refluxing Ru(DMSO) 4 Cl 2 with the corresponding ligand in EtOH. These Ru(III) and Ru(II) complexes, especially 1 b/2 b, exhibited high catalytic efficiency and broad functional group tolerance in ADC reactions of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. A detail mechanistic study indicated the Ru(III) complex was reduced into the Ru(II) species, which is the active catalytic center for ADC via a Ru−H/N−H bifunctional outer-sphere mechanism. This protocol provides a reliable, atom-economical and environmentally benign procedure for C−N and C−C bond formation.

Original languageEnglish
Pages (from-to)2500-2510
Number of pages11
JournalChemCatChem
Volume11
Issue number10
Early online date10 Apr 2019
DOIs
Publication statusPublished - 20 May 2019

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phosphine
Quinolines
Pyridines
Ruthenium
quinoline
phosphines
Pyridine
Amino alcohols
Amino Alcohols
ruthenium
pyridines
alcohols
Ligands
Dimethyl Sulfoxide
catalysts
ligands
Catalysts
Amines
Alcohols
synthesis

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Guo, Bin ; Yu, Tian Qi ; Li, Hong Xi ; Zhang, Shi Qi ; Braunstein, Pierre ; Young, David J. ; Li, Hai Yan ; Lang, Jian Ping. / Phosphine Ligand-Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions. In: ChemCatChem. 2019 ; Vol. 11, No. 10. pp. 2500-2510.
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title = "Phosphine Ligand-Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions",
abstract = "A series of phosphine-free Ru(III)/Ru(II) complexes of NH functionalized N ˄ N ˄ N pincer ligands exhibit excellent activity for acceptorless dehydrogenative coupling (ADC) of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. Ru(III) complexes [LRuCl 3 ] (L=6-(3-R 1 ,5-R 2 -1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2-amine; 1 a: R 1 =R 2 =H (L1); 1 b: R 1 =R 2 =Me (L2); 1 c: R 1 =H, R 2 =CF 3 (L3); 1 d: R 1 =H, R 2 =Ph (L4); 1b Me : L=6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-methyl-N-(pyridin-2-yl)pyridin-2-amine (L2 Me )) were obtained by refluxing RuCl 3 ⋅ xH 2 O with the corresponding ligand in EtOH. Five Ru(II) complexes [LRu(DMSO-κS)Cl 2 ] (2 a: L=L1; 2 b: L=L2; 2 c: L=L3; 2 d: L=L4; 2b Me : L=L2 Me ) were formed by reducing the corresponding Ru(III) complex in refluxing EtOH. The latter complexes could also be prepared directly by refluxing Ru(DMSO) 4 Cl 2 with the corresponding ligand in EtOH. These Ru(III) and Ru(II) complexes, especially 1 b/2 b, exhibited high catalytic efficiency and broad functional group tolerance in ADC reactions of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. A detail mechanistic study indicated the Ru(III) complex was reduced into the Ru(II) species, which is the active catalytic center for ADC via a Ru−H/N−H bifunctional outer-sphere mechanism. This protocol provides a reliable, atom-economical and environmentally benign procedure for C−N and C−C bond formation.",
keywords = "acceptorless dehydrogenative coupling reactions, bifunctional catalysts, pyridines, quinolines, Ru complexes",
author = "Bin Guo and Yu, {Tian Qi} and Li, {Hong Xi} and Zhang, {Shi Qi} and Pierre Braunstein and Young, {David J.} and Li, {Hai Yan} and Lang, {Jian Ping}",
year = "2019",
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day = "20",
doi = "10.1002/cctc.201900435",
language = "English",
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pages = "2500--2510",
journal = "ChemCatChem",
issn = "1867-3899",
publisher = "Wiley-VCH Verlag GmbH & Co. KGaA",
number = "10",

}

Phosphine Ligand-Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions. / Guo, Bin; Yu, Tian Qi; Li, Hong Xi; Zhang, Shi Qi; Braunstein, Pierre; Young, David J.; Li, Hai Yan; Lang, Jian Ping.

In: ChemCatChem, Vol. 11, No. 10, 20.05.2019, p. 2500-2510.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Phosphine Ligand-Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions

AU - Guo, Bin

AU - Yu, Tian Qi

AU - Li, Hong Xi

AU - Zhang, Shi Qi

AU - Braunstein, Pierre

AU - Young, David J.

AU - Li, Hai Yan

AU - Lang, Jian Ping

PY - 2019/5/20

Y1 - 2019/5/20

N2 - A series of phosphine-free Ru(III)/Ru(II) complexes of NH functionalized N ˄ N ˄ N pincer ligands exhibit excellent activity for acceptorless dehydrogenative coupling (ADC) of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. Ru(III) complexes [LRuCl 3 ] (L=6-(3-R 1 ,5-R 2 -1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2-amine; 1 a: R 1 =R 2 =H (L1); 1 b: R 1 =R 2 =Me (L2); 1 c: R 1 =H, R 2 =CF 3 (L3); 1 d: R 1 =H, R 2 =Ph (L4); 1b Me : L=6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-methyl-N-(pyridin-2-yl)pyridin-2-amine (L2 Me )) were obtained by refluxing RuCl 3 ⋅ xH 2 O with the corresponding ligand in EtOH. Five Ru(II) complexes [LRu(DMSO-κS)Cl 2 ] (2 a: L=L1; 2 b: L=L2; 2 c: L=L3; 2 d: L=L4; 2b Me : L=L2 Me ) were formed by reducing the corresponding Ru(III) complex in refluxing EtOH. The latter complexes could also be prepared directly by refluxing Ru(DMSO) 4 Cl 2 with the corresponding ligand in EtOH. These Ru(III) and Ru(II) complexes, especially 1 b/2 b, exhibited high catalytic efficiency and broad functional group tolerance in ADC reactions of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. A detail mechanistic study indicated the Ru(III) complex was reduced into the Ru(II) species, which is the active catalytic center for ADC via a Ru−H/N−H bifunctional outer-sphere mechanism. This protocol provides a reliable, atom-economical and environmentally benign procedure for C−N and C−C bond formation.

AB - A series of phosphine-free Ru(III)/Ru(II) complexes of NH functionalized N ˄ N ˄ N pincer ligands exhibit excellent activity for acceptorless dehydrogenative coupling (ADC) of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. Ru(III) complexes [LRuCl 3 ] (L=6-(3-R 1 ,5-R 2 -1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2-amine; 1 a: R 1 =R 2 =H (L1); 1 b: R 1 =R 2 =Me (L2); 1 c: R 1 =H, R 2 =CF 3 (L3); 1 d: R 1 =H, R 2 =Ph (L4); 1b Me : L=6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-methyl-N-(pyridin-2-yl)pyridin-2-amine (L2 Me )) were obtained by refluxing RuCl 3 ⋅ xH 2 O with the corresponding ligand in EtOH. Five Ru(II) complexes [LRu(DMSO-κS)Cl 2 ] (2 a: L=L1; 2 b: L=L2; 2 c: L=L3; 2 d: L=L4; 2b Me : L=L2 Me ) were formed by reducing the corresponding Ru(III) complex in refluxing EtOH. The latter complexes could also be prepared directly by refluxing Ru(DMSO) 4 Cl 2 with the corresponding ligand in EtOH. These Ru(III) and Ru(II) complexes, especially 1 b/2 b, exhibited high catalytic efficiency and broad functional group tolerance in ADC reactions of secondary alcohols with 2-aminobenzyl or γ-amino alcohols to quinolines and pyridines. A detail mechanistic study indicated the Ru(III) complex was reduced into the Ru(II) species, which is the active catalytic center for ADC via a Ru−H/N−H bifunctional outer-sphere mechanism. This protocol provides a reliable, atom-economical and environmentally benign procedure for C−N and C−C bond formation.

KW - acceptorless dehydrogenative coupling reactions

KW - bifunctional catalysts

KW - pyridines

KW - quinolines

KW - Ru complexes

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U2 - 10.1002/cctc.201900435

DO - 10.1002/cctc.201900435

M3 - Article

VL - 11

SP - 2500

EP - 2510

JO - ChemCatChem

JF - ChemCatChem

SN - 1867-3899

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ER -