Gold-Catalyzed Hydroarylation of N-Aryl Alkynamides for the Synthesis of 2-Quinolinones

Abstract

A mild method for the synthesis of 2-quinolinones via hydroarylation of N-aryl alkynamides is reported. While traditional methods have relied on the use of strong Brønsted or Lewis acids, this report describes the development of mild reaction conditions that yield 2-quinolinones in good to excellent yield using a commercially available gold catalyst. Substrates bearing a variety of functional groups are presented, with N-substitution proving to be key to the reactivity of several substrates.

Catalytic Gold Chemistry: From Simple Salts to Complexes for Regioselective C−H Bond Functionalization

“…(1)). [184] González et al demonstrated that the Au(I)-catalyzed intramolecular hydroarylation of N-(3-iodoprop-2-ynyl)-N-tosylanilines affords two regioisomeric iodinated 1,2-dihydroquinolines; one as a consequence of a direct cyclization route and the other was obtained by the associated 1,2-iodide migration. Apparently, the ratio of these two regioisomers can somewhat be modified by changing the auxiliary phosphine or NHC ligands on the gold(I) metal center.…”

Synthesis of 4-Substituted-1,2-Dihydroquinolines by Means of Gold-Catalyzed Intramolecular Hydroarylation Reaction of N-Ethoxycarbonyl-N-Propargylanilines

“…Very likely, the control of ortho/para site-selectivity in these substrates is the result of the different coordination modes of the gold catalyst influenced by sterics and electronics of the auxiliary ligand. The prowess of electron-rich bulk ligands in pushing the π-system toward the para C–H bond through a Au(I)-bicoordinate activation was also explored in the 6- endo - dig gold catalyzed hydroarylation of functionalized N -aryl alkynamides ( Figure 3 ) [ 30 ].…”

“…Molecules 2021, 26, x FOR PEER REVIEW 7 of 13 the 6-endo-dig gold catalyzed hydroarylation of functionalized N-aryl alkynamides (Figure 3) [30]. Indeed, according to the literature [13], the gold catalyzed IMHA proceeds through a Friedel-Crafts type mechanism: η 2 -coordination of alkyne moiety affords complex I, which undergoes an electrophilic aromatic substitution to give the Wheland-type intermediate II.…”

Weak Base-Promoted Lactamization under Microwave Irradiation: Synthesis of Quinolin-2(1H)-ones and Phenanthridin-6(5H)-ones

“…6 Fujiwara and Vadola also demonstrated palladium- and gold-catalyzed intramolecular hydroarylation of N -aryl alkynamides leading to quinolin-2(1 H )-ones (Scheme 1, route d). 7 Acetanilides were found to be coupled and cyclized with propiolates and acrylates in the presence of a ruthenium catalyst along with a carboxylic acid to form quinolin-2(1 H )-ones (Scheme 1, route e). 8 Such a similar coupling and cyclization was also exemplified by the iridium-catalyzed annulation of N -arylcarbamoyl chlorides with internal alkynes (Scheme 1, route f).…”