Cobalt(III)‐Catalyzed Directed CH Coupling with Diazo Compounds: Straightforward Access towards Extended π‐Systems

Abstract

The first highly efficient and scalable cobalt-catalyzed directed C-H functionalization with carbene precursors is presented. This methodology provides a modular route towards a new class of conjugated polycyclic hydrocarbons with tunable emission wavelengths both in solution and in the solid state.

Cobalt(III)‐Catalyzed Dehydrative [4+2] Annulation of Oxime with Alkyne by CH and NOH Activation

“…[3g,i, 4] However,m ore recently the importance of high-valent Co III -catalyzed chelate-assisted CÀHb ond functionalizations withouta ny base or reductant have been demonstrated by Glorius, Ackermann, Ellman, and Chang following pioneering work by Matsunaga and Kanai. [5] Isoquinolinesa re found in many pharmaceuticals and biologicallya ctive alkaloids.…”

“…Use of 10 mol %o ft he Cp*Co III catalyst using MeOH or EtOH as solvent did not promote the reaction of oxime 1a with tolane (2a)( entries 1a nd 2). Changeo fs olvent and increasing the temperature moderately improves the yield (entries [3][4][5]. While employing 2,2,2-trifluoroethanol (TFE) as solventa t1 20 8Cs ignificantly improves the yield of 3aa (65 %; entry 5).…”

Substrate‐Directed C‐H Functionalization of 2‐Aryl Pyridines by Transition Metal Complexes

“…In addition, pyridines with both donating and withdrawing groups also showed a broad functional group compatible to obtain the coupling products in good to excellent yields. In 2015, Feng et al reported another methodology using Pd(II)-catalyzed orthoacylation of 2-aryl pyridines (3) with arylglycines (88). Authors used Cu(OAc) 2 and K 2 S 2 O 8 to afford benzophenones (89) in the reaction.…”

“…[88] Furthermore, this facile synthetic approach resulted in the discovery of a new family of extended p-systems. For the coupling of 2-phenyl pyridine (3) with dimethyl diazomalonate, the catalyst loading could be further decreased to 1 mol% without a significant decrease in yield.…”

Palladium‐Catalyzed Intramolecular Carbene Insertion into C(sp3)−H Bonds

“…[4] Although other metals have emerged as potentially useful catalysts for this type of transformation, [5][6][7][8][9][10] the use of palladium has been restricted to ac ouple of examples of a-diazo b-ketoester insertion into C(sp 2 )ÀH bonds. [11,12] This fact is highly surprising if we take into account the great success of Pd catalysis in cross-coupling reactions of diazo compounds with either organic halides or arylboronic acids.…”