Synthesis of Ruthenium(II) 2,6-Bis(imino)pyridyl Complexes for C-H Amination of Sulfamate Esters
Year: 2011
Type: article
Abstract: A family of ruthenium(II) 2,6-bis(imino)pyridyl complexes have been developed as a novel catalyst framework for C-H amination.Their synthesis and evaluation is herein described.The reactivity of these catalysts is heavily dependent upon the electronics of the ligand.These complexes are capable of functionalizing the benzylic protons of sulfamate esters with good conversion.2][3][4][5][6] Despite recent advances in this area, many challenges remain, particularly with respect to substrate generality and intermolecular amination.In an attempt to address these challenges, our group has focused on the development of novel catalyst frameworks for these reactions. 7We have previously established the efficacy of ruthenium(II) pyridinebisoxazoline (pybox) complexes for the formation of carbon-nitrogen bonds and were intrigued by the role of the ligand in the transformation.2,6-Bis(imino)pyridyl ligands are isoelectronic with pybox ligands, but the ligands themselves have been shown to participate in redox events and therefore may help stabilize the reactive imido intermediate. 8While a small number of ruthenium(II) 2,6-bis(imino)pyridyl complexes are known, 9-11 their potential for C-H amination has not been reported.Herein we report the synthesis and evaluation of a family of ruthenium(II) 2,6-bis(imino)pyridyl complexes as new catalysts for amination of benzylic C-H bonds.A series of 2,6-bis(imino)pyridyl ligands were synthesized to study the effect of both steric and electronic variations around the aniline ring on the catalysts activity towards C-H amination.All ligands were generated from the condensation of 2,6-diacetylpyridine with the corresponding commercially available aniline. 12 Ligands lacking ortho substitution (1, 4, and 5), as well as ligands with methyl (2) and isopropyl(3) substituents at both ortho positions were all prepared to give three distinct levels of steric inhibition N N N Ru Cl Cl CO N N N Ru Cl Cl
Source: Heterocycles
Authors: Simon B. Blakey, Jennifer L. Bon
Institution: Emory University
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W2950924720