ChemInform Abstract: Cobalt Catalyzed sp³ C—H Amination Utilizing Aryl Azides.

Abstract

Cobalt Catalyzed sp 3 C-H Amination Utilizing Aryl Azides. -A dinuclearCo(II) complex is capable of selective C-H amination to form indolines from aryl azides at low catalyst loading. The reaction is tolerant of medicinally relevant heterocycles, such as pyridine and indole, and can be used to form 5-, 6-, and 7-membered rings. The synthetic versatility obtained using low loadings of an earth abundant transition metal complex represents a significant advance in catalytic C-H amination technology. -(VILLANUEVA, O.; WELDY, N. M.; BLAKEY*, S. B.; MACBETH, C. E.; Chem. Sci. 6 (2015) 11, 6672-6675, http://dx.

Transition Metal-Catalyzed C–H Amination: Scope, Mechanism, and Applications

“…In 2015, Blakey and MacBeth revealed a novel catalyst system based on a dinuclear Co(II) complex 55 bearing redoxactive anilide ligands (Scheme 106). 327 Given that the catalyst was effective for the catalytic oxygen atom transfer via multielectron processes, 328 the authors sought to investigate an analogous amino transfer process with organic azides. Using an aryl azide possessing a 2-homobenzyl substituent, an intramolecular C−H amination affording indoline products was successfully achieved.…”

Accessing Pentagonal Bipyramidal Geometry with Pentadentate Pincer Amido-bis(amidate) Ligands in Group IV and V Early Transition Metal Complexes

“…45−47 The proposed ligand with phenyl substituents (1e) has already been used to prepare cobalt complexes binding in a κ-N amidate fashion. 48,49 Herein, we report the synthesis and characterization of new trianionic pentadentate proligands 1a− 1d which have increasing degrees of steric bulk and their corresponding pentagonal bipyramidal titanium compounds 2a−2d. Using the most sterically demanding 2,4,6-trisisopropylphenyl substituted proligand (1d), we have been able to isolate and characterize complexes of larger early transition metals [3d (Zr), 4d (Hf), Nb 5d (Nb), 6d (Ta)] in which the metals are incorporated into the chelating pocket of the ligand, giving rise to stable mononuclear complexes.…”