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
N1 - Funding Information:
The authors express their appreciation to the Ministry of Science and Technology of Taiwan (MOST 105-2113-M-018-005 ) for financial assistance. We also thank the National Changhua University of Education for providing the facility of X-ray diffractometer and NMR spectrometer and the National Center for High-performance Computing for supporting the CCDC database searching. Appendix A
Funding Information:
The authors express their appreciation to the Ministry of Science and Technology of Taiwan (MOST 105-2113-M-018-005) for financial assistance. We also thank the National Changhua University of Education for providing the facility of X-ray diffractometer and NMR spectrometer and the National Center for High-performance Computing for supporting the CCDC database searching.
Publisher Copyright:
© 2018
PY - 2018/4/15
Y1 - 2018/4/15
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.
KW - Alcohol amination
KW - Intramolecular ring current effect
KW - Ruthenium
KW - Spin saturation transfer
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U2 - 10.1016/j.jorganchem.2018.02.029
DO - 10.1016/j.jorganchem.2018.02.029
M3 - Article
AN - SCOPUS:85042669177
SN - 0022-328X
VL - 861
SP - 10
EP - 16
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
ER -