Cobalt-Catalyzed Remote C-4 Functionalization of 8-Aminoquinoline Amides with Ethers via C–H Activation under Visible-Light Irradiation. Access to α-Heteroarylated Ether Derivatives

Abstract

A cobalt-catalyzed selective remote C-4 alkylation of 8-aminoquinoline amides via C-H activation under irradiation with a CFL lamp in the presence of eosin Y at room temperature has been achieved. A series of pharmaceutically important C-4 quinoline amide-substituted ether derivatives has been obtained by this procedure. The C-4 functionalization of quinoline amides with inert ether is of much significance and was not reported earlier.

TEMPO-Catalyzed Aminophosphinoylation of Ethers via Tandem C(sp3)–H and C(sp3)–O Bond Cleavage

“…Recently, the cross-coupling reaction involving α-C–H functionalization of ether has emerged as a powerful and attractive protocol for construction of the C–X (X = C, S, N, P) bond . In most cases, the C–O bond cleavage of ether does not occur, and the ether structural unit was introduced to the organic framework via C–H functionalization of ethers. , So far, a few synthetic methods have been reported for difunctionalization of ethers via tandem C–H and C–O bond cleavage, in which transition-metal catalysts, strong oxidants, or high reaction temperature are usually required. − For example, Li and co-workers described Fe-catalyzed reactions of indoles with ethers for the synthesis of 1,1-bis-indolylmethane derivatives via C–H bond oxidation and C–O bond cleavage in the presence of ( t -BuO) 2 . Wang reported Mn-catalyzed three-component synthesis of 1,5-amino/keto alcohols from Grignard reagents, imines/nitriles, and tetrahydrofuran (THF) through C–H and C–O bond cleavage of THF .…”

Visible-Light-Triggered Decarboxylative Alkylation of 8-Acylaminoquinoline with N-Hydroxyphthalimide Ester

“…however, primary alkyl acids did not participate in the reaction. Recently, Ranu 12 reported a cobalt-catalyzed selective remote C-4 alkylation of 8-aminoquinoline amides via C-H activation with irradiation with a CFL lamp (Scheme 1c). Consequently, it is highly desirable to investigate both mild and convenient methods for synthesizing alkylated, especially primary-alkylated, 8-aminoquinoline derivatives, which could further promote the application of 8-aminoquinolines in new drug discovery and synthesis.…”

Visible-Light-Induced Regioselective Cross-Dehydrogenative Coupling of 2H-Indazoles with Ethers

“…The synthesis of cyclic ether-functionalized complex organic molecules becomes a challenging task in synthetic organic chemistry due to the inertness of simple ethers. Although numerous methodologies have been developed for the α-C–H functionalization of ethers, most of these approaches require transition-metal catalysts, ligands, and harsh reaction conditions …”