Brønsted Acid-Catalyzed Reaction of N-arylnaphthalen-2-amines with Quinone Esters for the Construction of Carbazole and C–N Axially Chiral Carbazole Derivatives

Abstract

We demonstrated here an efficient synthetic method of carbazole derivatives from readily available Narylnaphthalen-2-amines and quinone esters catalyzed by Brønsted acid. With this strategy, a series of carbazole derivatives were obtained in good to excellent yields (76 to >99) under mild conditions. Large scale reaction illustrated the synthetic utility of this protocol. Meanwhile, a series of C−N axially chiral carbazole derivatives were also constructed in moderate to good yields (36− 89% yield) with moderate to excellent atroposelectivities (44−94% ee) by using chiral phosphoric acid as a catalyst, which provides a novel strategy for the atroposelective construction of C−N axially chiral compounds and a new member of the C−N atropisomers.

Enantioselective Construction of Axially Iodobenzocarbazole Derivatives by Stereogenic‐at‐Cobalt(III)‐Complex‐Catalyzed Iodoarylation of Alkynes

“…[15a,18] The alkyne 1 were prepared according to the procedure reported. [10a,19] 1 H-NMR, 13 C-NMR, and 19 F-NMR spectra were recorded on an Agilent 600 NMR spectrometer at 600 MHz, 151 MHz, and 564 MHz using CDCl 3 as solvent, respectively. 1 H-NMR data are reported as follows: δ, chemical shift; coupling constants (J are given in Hertz, Hz) and integration.…”

“…Chemical shifts were reported in ppm from the tetramethylsilane (TMS) with the solvent resonance as internal standard [ 1 H δ = 0.00]. What should be noted is that all petroleum ether and ethyl acetate using for flash chromatography purchased from Chinese commercial sources were redistilled twice before using, even though the trace amount of residue of impurities such as H-grease and silicone grease could still be seen on NMR spectra of some products ( 1 H NMR: δ 1.25/0.84-0.87 and 0.07; 13 atoms were refined anisotropically and all the hydrogen atoms were assigned in idealized locations. Optical rotations were recorded on an Anton Paar MCP-100 polarimeter.…”

“…To date, only a few successful examples using special substrates have been demonstrated. [10][11][12][13] Most of the approaches need to utilize existing carbazole moieties as the starting materials. For an instance, an organocatalytic atroposelective CÀ H amination of azonaphthalene with carbazole derivatives was realized by Tan's group in 2020 (Scheme 1b).…”

“…[12] More recently, Liu et al exhibited the construction of axially chiral carbazole derivatives via a cascade reaction of arylamines with quinone esters by using chiral phosphoric acids (CPA) as catalysts. [13] Despite these achievements, the research domain for synthesizing axially chiral carbazoles is still in its infancy. Thus, further developing efficient strategies is of great significance.…”

“…To date, only a few successful examples using special substrates have been demonstrated [10–13] . Most of the approaches need to utilize existing carbazole moieties as the starting materials.…”