Rhodium-Catalyzed Oxidative Cycloaddition of Benzamides and Alkynes via C−H/N−H Activation

Abstract

The oxidative cycloaddition of benzamides and alkynes has been developed. The reaction utilizes Rh(III) catalysts in the presence of Cu(II) oxidants, and is proposed to proceed by N-H metalation of the amide followed by ortho C-H activation. The resultant rhodacycle undergoes alkyne insertion to form isoquinolones in good yield. The reaction is tolerant of extensive substitution on the amide, alkyne and arene, including halides, silyl ethers, and unprotected aldehydes as substituents. Unsymmetrical alkynes proceed with excellent regioselectivity, and heteroaryl carboxamides are tolerated leading to intriguing scaffolds for medicinal chemistry. A series of competition experiments shed further light on the mechanism of the transformation and reasons for selectivity.

Rhodium‐Catalyzed Oxidative Olefination of CH Bonds in Acetophenones and Benzamides

“…Herein we report on the oxidative olefination of acetophenones and electronically related benzamides [9] with a broad range of olefins.…”

Solvent‐Free Ruthenium(II)‐Catalyzed C–H Activation: Synthesis of Alkenylarylpyrazole Derivatives

“…However, the oxidative alkenylation of heteroarenes is named the Moritani-Fujiwara reaction. [8,9] In this regard, different palladium [10][11][12][13] and rhodium catalysts [14][15][16] have already been used to promote the oxidative alkenylation of heteroarenes with a variety of directing groups, namely, imines, [17,18] amines, [19] and carboxylates. [20,21] Rutheniumcatalyst-directed arylation of unactivated C-H bonds with phenols was reported by Ackermann.…”

Nickel-Catalyzed C–H Bond Functionalization Utilizing an N,N′-Bidentate Directing Group

“…A similar transformation was previously reported Scheme 2 Cyclometalation using NiBr 2 Scheme 3 Imidazolium C-H/alkene coupling reaction Fig. 1 Representative substrates applicable to the Ni-catalyzed functionalization of C-H bonds Nickel-Catalyzed C-H Bond Functionalization Utilizing an N,N using Rh(III) as the catalyst [23,24]. However, the reaction does not require the addition of a metal oxidant or an intramolecular sacrificed oxidizing substituent in the substrate, in contrast to the Rh(III) system.…”