Diverse Reactivity in a Rhodium(III)‐Catalyzed Oxidative Coupling of N‐Allyl Arenesulfonamides with Alkynes

Abstract

Scheme 2. Intermediacy of a 1,2-dihydropyridine. Scheme 3. Mechanism of the formation of 3-sulfonated pyridines.

Rhodium‐Catalyzed Synthesis of Amides from Aldehydes and Azides by Chelation‐Assisted CH Bond Activation

“…Recently, several investigations revealed that Rh III complexes undergo chelation-assisted electrophilic metalation of ortho CA C H T U N G T R E N N U N G (sp 2 )ÀH bonds to form arylrhodium complexes, [14] which may be coupled to a variety of reagents such as aldehydes, [15] imines, [16] isocyanates, [17] diazomalonates, [18] azides, [19] alkenes, and alkynes (Scheme 1 b). [20] Therefore, herein, we report the first example of Rh III -catalyzed amidation of aldehydes with azides as an amine source in the presence of air (Scheme 1 c). This catalytic aldehyde C À H amidation proceeds in the absence of external oxidants and additives, under mild and neutral reaction, conditions with high functional group tolerance, and releases N 2 as the single byproduct.…”

Rhodium(III)-Catalyzed Dearomatizing (3 + 2) Annulation of 2-Alkenylphenols and Alkynes

“… 5 The discovery of new cycloadditions based on the activation of olefinic or aliphatic C–H bonds, which would allow the formation of carbocyclic products other than fused aromatic systems, is of foremost interest. 6 …”

Rhodium(III)‐Catalyzed CC Coupling between Arenes and Aziridines by CH Activation

“…Very recently, Rh III complexes have stood out as efficient catalysts for the CÀH activation of a large array of CÀH bonds. [3] Along with the extensively studied rhodium(III)-catalyzed functionalization of CÀH bonds with alkynes [4] and alkenes, [5] the coupling partners have been extended to other substrates, such as imines, [6] aldehydes, [7] isocyanates, [8] allenes, [9] sulfonyl azides, [10] chloroamines, and N-halosuccinimides, [11] and carbene precursors such as diazomalonates [12] in redox-neutral reactions (Scheme 1). These coupling partners are electrophiles that typically react with Grignard reagents to allow CÀC and CÀN couplings starting from arenes.…”