Cobalt catalyzed sp³ C–H amination utilizing aryl azides

Abstract

A dinuclear Co(ii) complex supported by a modular, tunable redox-active ligand system is capable of selective C–H amination to form indolines from aryl azides in good yields at low (1 mol%) catalyst loading.

High‐Valent‐Cobalt‐Catalyzed C−H Functionalization Based on Concerted Metalation–Deprotonation and Single‐Electron‐Transfer Mechanisms

“…Around the same time, Blakey and co‐workers reported an efficient method of selective C−H amination of aryl azides ( 102 ) to form indulines ( 103 ) in good yields by using the dinuclear Co II complex catalyst (1 mol %, Scheme ) . The reaction tolerated medicinally relevant heterocycles, such as pyridine and indole, which could be successfully applied to form 5‐, 6‐, and 7‐membered rings with low cobalt loadings, representing a significant advance in C−H amination catalysis.…”

Cobalt‐Porphyrin‐Catalysed Intramolecular Ring‐Closing C−H Amination of Aliphatic Azides: A Nitrene‐Radical Approach to Saturated Heterocycles

“…[9][10][11][12] More recently,a nd mostr elevantt ot he investigationsd escribed in this paper,s ome interesting examples involving intramolecular amination of CÀHb onds using primary aliphatic organic azides (RCH 2 N 3 )a st he "nitrene" source werer eported (see Figure 1). [13][14][15] Although these examples provide interesting lead-reactivity for the synthesis of saturated heterocycles (in particulart he system reported by Betley and co-workers [13a] ), there are still an umber of hurdles to overcome; (1) mosto ft he previously reported catalysts fort his reactiona re highly sensitivet oa ir and water and require relatively high catalystl oadings, thus resulting in low catalytic turnover numbers (TONs); [13][14][15] (2) several of the reported catalysts produce significant amountso f (Boc-protected) linear amines as undesired side products; [13][14][15] (3) asymmetric versions of intramolecularr ing-closing CÀH bond amination reactions of unactivated aliphatic azides are unknown;a nd (4) relativelyl imited mechanistic information for these types of reactions is available to guide scientists in finding solutionst ot he above challenges, thus hampering the designa nd development of more efficient catalysts. Cobalt porphyrin systems have been reported forr elated CÀHf unctionalization protocols.…”

Next‐Generation D2‐Symmetric Chiral Porphyrins for Cobalt(II)‐Based Metalloradical Catalysis: Catalyst Engineering by Distal Bridging

“…[7] In parallel, the application of Co II -MRC to organic azides has resulted in the disclosure of an ew radical pathway for catalytic olefin aziridination involving a-Co III -aminyl radicals (B1) [8] and g-Co III -alkyl radicals (B2)a sk ey intermediates (Scheme 1B). [7,9,10] In practice,t he formidable challenge associated with controlling the stereoselectivity of radical reactions can essentially be translated into as olvable problem of catalyst design and development. [7,9,10] In practice,t he formidable challenge associated with controlling the stereoselectivity of radical reactions can essentially be translated into as olvable problem of catalyst design and development.…”