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

All Science Journal Classification (ASJC) codes

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

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