Catalytic amination of benzyl alcohol using ruthenium cymene compounds containing bidentate N,O-donor ancillary ligands

Chi Meng Hsiao, Yun Fan Chen, Chia Her Lin, Ching-Han Hu, You Ru Cai, Jui-Hsien Huang

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

A series of ruthenium-cymene derivatives subjecting [Ru(η6-cymene)Cl2]2 and substituted bidentate N,O donor precursors have been synthesized and characterized. Reacting [Ru(η6-cymene)Cl2]2 with two equivalents the lithium salt of phenyl keto-amine ligands LiL1∼LiL3 resulted in the formation of [Ru(η6-cymene)(L)Cl] (1–3). Similarly, the reaction between [Ru(η6-cymene)Cl2]2 and two equivalents of LiL4 or NaL5 afforded compounds {Ru(η6-cymene)[L4)]Cl} (4) and [Ru(η6-cymene)(L5)Cl] (5). The 1H NMR chemical shifts of aromatic protons of the cymene fragment for compounds 1–5 fell in the range δ 5.54–3.58, showing chemical shifts farther upfield than the corresponding protons of [Ru(η6-cymene)Cl2]2 due to the intramolecular ring current effect. The 2,6-diisopropylphenyl substituted pheny lketo-amine ligand of compound 3 shows a slow C-N bond rotation with the rotation rate constant at ca. 4.62 s−1. The catalytic aminations of benzyl alcohol with benzylamine using compounds 1–3 as catalysts resulted in higher conversion than using compounds 4 and 5. Two products, PhCH = NCH2Ph and HN(CH2Ph)2 were detected, with PhCH = NCH2Ph being the major product. When benzyl alcohol was reacted with phenylamine in the presence of compounds 1–5, the conversions are all greater than 60% and PhCH = NPh was the major product. While sterically hindered 2,6-diisopropylaniline appeared in alcohol amination reactions in the presence of catalysts, no imine or amine products were detected.

Original languageEnglish
Pages (from-to)10-16
Number of pages7
JournalJournal of Organometallic Chemistry
Volume861
DOIs
Publication statusPublished - 2018 Apr 15

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Ruthenium Compounds
Ruthenium compounds
ruthenium compounds
Benzyl Alcohol
Amination
Amines
alcohols
Alcohols
Ligands
Chemical shift
amines
ligands
Protons
Aniline Compounds
products
chemical equilibrium
Catalysts
Imines
Ruthenium
Aniline

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

@article{7eefdcaadb7748d490546d9015b0c37d,
title = "Catalytic amination of benzyl alcohol using ruthenium cymene compounds containing bidentate N,O-donor ancillary ligands",
abstract = "A series of ruthenium-cymene derivatives subjecting [Ru(η6-cymene)Cl2]2 and substituted bidentate N,O donor precursors have been synthesized and characterized. Reacting [Ru(η6-cymene)Cl2]2 with two equivalents the lithium salt of phenyl keto-amine ligands LiL1∼LiL3 resulted in the formation of [Ru(η6-cymene)(L)Cl] (1–3). Similarly, the reaction between [Ru(η6-cymene)Cl2]2 and two equivalents of LiL4 or NaL5 afforded compounds {Ru(η6-cymene)[L4)]Cl} (4) and [Ru(η6-cymene)(L5)Cl] (5). The 1H NMR chemical shifts of aromatic protons of the cymene fragment for compounds 1–5 fell in the range δ 5.54–3.58, showing chemical shifts farther upfield than the corresponding protons of [Ru(η6-cymene)Cl2]2 due to the intramolecular ring current effect. The 2,6-diisopropylphenyl substituted pheny lketo-amine ligand of compound 3 shows a slow C-N bond rotation with the rotation rate constant at ca. 4.62 s−1. The catalytic aminations of benzyl alcohol with benzylamine using compounds 1–3 as catalysts resulted in higher conversion than using compounds 4 and 5. Two products, PhCH = NCH2Ph and HN(CH2Ph)2 were detected, with PhCH = NCH2Ph being the major product. When benzyl alcohol was reacted with phenylamine in the presence of compounds 1–5, the conversions are all greater than 60{\%} and PhCH = NPh was the major product. While sterically hindered 2,6-diisopropylaniline appeared in alcohol amination reactions in the presence of catalysts, no imine or amine products were detected.",
author = "Hsiao, {Chi Meng} and Chen, {Yun Fan} and Lin, {Chia Her} and Ching-Han Hu and Cai, {You Ru} and Jui-Hsien Huang",
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Catalytic amination of benzyl alcohol using ruthenium cymene compounds containing bidentate N,O-donor ancillary ligands. / Hsiao, Chi Meng; Chen, Yun Fan; Lin, Chia Her; Hu, Ching-Han; Cai, You Ru; Huang, Jui-Hsien.

In: Journal of Organometallic Chemistry, Vol. 861, 15.04.2018, p. 10-16.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Catalytic amination of benzyl alcohol using ruthenium cymene compounds containing bidentate N,O-donor ancillary ligands

AU - Hsiao, Chi Meng

AU - Chen, Yun Fan

AU - Lin, Chia Her

AU - Hu, Ching-Han

AU - Cai, You Ru

AU - Huang, Jui-Hsien

PY - 2018/4/15

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N2 - A series of ruthenium-cymene derivatives subjecting [Ru(η6-cymene)Cl2]2 and substituted bidentate N,O donor precursors have been synthesized and characterized. Reacting [Ru(η6-cymene)Cl2]2 with two equivalents the lithium salt of phenyl keto-amine ligands LiL1∼LiL3 resulted in the formation of [Ru(η6-cymene)(L)Cl] (1–3). Similarly, the reaction between [Ru(η6-cymene)Cl2]2 and two equivalents of LiL4 or NaL5 afforded compounds {Ru(η6-cymene)[L4)]Cl} (4) and [Ru(η6-cymene)(L5)Cl] (5). The 1H NMR chemical shifts of aromatic protons of the cymene fragment for compounds 1–5 fell in the range δ 5.54–3.58, showing chemical shifts farther upfield than the corresponding protons of [Ru(η6-cymene)Cl2]2 due to the intramolecular ring current effect. The 2,6-diisopropylphenyl substituted pheny lketo-amine ligand of compound 3 shows a slow C-N bond rotation with the rotation rate constant at ca. 4.62 s−1. The catalytic aminations of benzyl alcohol with benzylamine using compounds 1–3 as catalysts resulted in higher conversion than using compounds 4 and 5. Two products, PhCH = NCH2Ph and HN(CH2Ph)2 were detected, with PhCH = NCH2Ph being the major product. When benzyl alcohol was reacted with phenylamine in the presence of compounds 1–5, the conversions are all greater than 60% and PhCH = NPh was the major product. While sterically hindered 2,6-diisopropylaniline appeared in alcohol amination reactions in the presence of catalysts, no imine or amine products were detected.

AB - A series of ruthenium-cymene derivatives subjecting [Ru(η6-cymene)Cl2]2 and substituted bidentate N,O donor precursors have been synthesized and characterized. Reacting [Ru(η6-cymene)Cl2]2 with two equivalents the lithium salt of phenyl keto-amine ligands LiL1∼LiL3 resulted in the formation of [Ru(η6-cymene)(L)Cl] (1–3). Similarly, the reaction between [Ru(η6-cymene)Cl2]2 and two equivalents of LiL4 or NaL5 afforded compounds {Ru(η6-cymene)[L4)]Cl} (4) and [Ru(η6-cymene)(L5)Cl] (5). The 1H NMR chemical shifts of aromatic protons of the cymene fragment for compounds 1–5 fell in the range δ 5.54–3.58, showing chemical shifts farther upfield than the corresponding protons of [Ru(η6-cymene)Cl2]2 due to the intramolecular ring current effect. The 2,6-diisopropylphenyl substituted pheny lketo-amine ligand of compound 3 shows a slow C-N bond rotation with the rotation rate constant at ca. 4.62 s−1. The catalytic aminations of benzyl alcohol with benzylamine using compounds 1–3 as catalysts resulted in higher conversion than using compounds 4 and 5. Two products, PhCH = NCH2Ph and HN(CH2Ph)2 were detected, with PhCH = NCH2Ph being the major product. When benzyl alcohol was reacted with phenylamine in the presence of compounds 1–5, the conversions are all greater than 60% and PhCH = NPh was the major product. While sterically hindered 2,6-diisopropylaniline appeared in alcohol amination reactions in the presence of catalysts, no imine or amine products were detected.

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