Ruthenium(II) complexes bearing pyridine-functionalized N-heterocyclic carbene ligands: Synthesis, structure and catalytic application over amide synthesis

Content Provider	Semantic Scholar
Author	Nirmala, Muthukumaran Viswanathamurthi, Periasamy
Copyright Year	2016
Abstract	AbstractA series of four imidazolium salts was synthesized by the reaction of 2-bromopyridine with 1-substituted imidazoles. These imidazolium salts (1a–d) were successfully employed as ligand precursors for the syntheses of new ruthenium(II) complexes bearing neutral bidentate ligands of N-heterocyclic carbene and pyridine donor moiety. The NHC-ruthenium(II) complexes (3a–d) were synthesized by reacting the appropriately substituted pyridine-functionalized N-heterocyclic carbenes with Ag2O forming the NHC–silver bromide in situ followed by transmetalation with [RuHCl(CO)(PPh3)3]. The new complexes were characterized by elemental analyses and spectroscopy (IR, UV-Vis,1H,13C,31P-NMR) as well as ESI mass spectrometry. Based on the spectral results, an octahedral geometry was assigned for all the complexes. The complexes were shown to be efficient catalysts for the one-pot conversion of various aldehydes to their corresponding primary amides with good to excellent isolated yields using NH2OH.HCl and NaHCO3. The effects of solvent, base, temperature, time and catalyst loading were also investigated. A broad range of amides were successfully synthesized with excellent isolated yields using the above optimized protocol. Notably, the complex 3a was found to be a very efficient and versatile catalyst towards amidation of a wide range of aldehydes. Graphical Abstract A series of ruthenium(II) complexes (3a-d) bearing pyridine functionalized N-heterocyclic carbene ligand was synthesized and characterized by FT-IR, NMR and ESI-Mass. The catalytic study of complexes (3a-d) towards one-pot conversion of various aldehydes to their corresponding primary amides was studied. This new protocol is effective broad range of amides were successfully synthesized in good to excellent yields.
Starting Page	1725
Ending Page	1735
Page Count	11
File Format	PDF HTM / HTML
DOI	10.1007/s12039-016-1169-y
Alternate Webpage(s)	https://www.ias.ac.in/article/fulltext/jcsc/128/11/1725-1735
Alternate Webpage(s)	https://doi.org/10.1007/s12039-016-1169-y
Volume Number	128
Journal	Journal of Chemical Sciences
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article