Cobalt-Catalyzed Ortho-Arylation of Aromatic Imines with Aryl Chlorides

Abstract

An ortho-arylation reaction of aromatic imines with aryl chlorides has been achieved using a cobalt-N-heterocyclic carbene catalyst in combination with a neopentyl Grignard reagent. The reaction takes place at room temperature to afford biaryl products in moderate to good yields.

Cobalt‐Catalyzed CH Bond Functionalizations with Aryl and Alkyl Chlorides

“…[4,14] Given our interest in C À H bond arylations with user-friendly aryl chlorides, [16] we consequently probed our recently developed reaction conditions [13] for the cobalt-catalyzed CÀH bond arylation with challenging chlorides as the electrophilic substrates. A very recent report from Yoshikai and co-workers on useful cobalt-catalyzed arylations of ketimines [17] prompted us to now disclose a full account on a versatile cobalt catalyst for high-yielding CÀH bond arylations of heteroaryl-substituted arenes with cost-economical aryl chlorides. Further notable features of the user-friendly cobalt catalyst include remarkably mild reaction temperatures (23 8C), [18] and widely applicable CA C H T U N G T R E N N U N G (sp 2 ) À CA C H T U N G T R E N N U N G (sp 3 ) bond formations with challenging b-hydrogen-containing primary and secondary alkyl [19,20] chlorides-transformations that hitherto were solely accomplished by using secondary benzamides, along with primary alkyl chlorides.…”

Cobalt‐Catalyzed CH Arylations with Weakly‐Coordinating Amides and Tetrazoles: Expedient Route to Angiotensin‐II‐Receptor Blockers

“…[6] In recent years, inexpensive cobalt complexes have emerged as powerful catalysts for CÀHf unctionalizations with organic electrophiles. [7][8][9] However,i ns pite of considerable progress, [7,[10][11][12] cobalt-catalyzed CÀHa rylations con-…”

“…Thus far,a ll reported cobaltcatalyzed direct arylationsw ith organic (pseudo)halides were accomplished with either of the two N-heterocyclic carbene (NHC) [20,21] preligands IMesHCl( 6a)o rI PrHCl (6b). [10][11][12] However,p religands 6a and 6b delivered the desired product 5aa only in unsatisfactory low yields, even at ar elativelyh igh catalyst loading of 10 mol %(entries 1and 2). Asimilarobservation was made when employing the saturateda nalogues sIMesHCl (6c), and sIPrHCl (6d)( entries 3a nd 4), or the tertiary phosphine PPh 3 (entry 5).…”

Mild metal-catalyzed C–H activation: examples and concepts

“…50 In addition, coupling with vinylsilanes and aliphatic olefins at room temperature or 60 1C, respectively, could also be performed when monophosphine ligands were replaced by N,N-bidentate ancillaries such as phenanthroline or neocuproine, affording the linear products. 51 On the other hand, NHCs were found to be superior ligands to mono-phosphines for the ortho-arylation or benzamides with chloroarenes, 52 smoothly delivering the desired products at RT whereas a reaction temperature of 80 1C was required using PEt 3 as ligand. A similar system was also successfully applied in alkylation reactions with alkyl chloride and bromide coupling partners 53 and in a direct ring-opening process with aziridines.…”