Synthesis of Carbazolequinones by Formal [3 + 2] Cycloaddition of Arynes and 2-Aminoquinones

Abstract

A formal cycloaddition reaction for the synthesis of biologically and pharmaceutically important carbazolequinones via the annulation of aminoquinones with arynes has been developed. This practical and metal-free cascade reaction proceeds through successive C-C/C-N bond formations. Moreover, this novel method has been utilized for the concise synthesis of bioactive murrayaquinone A and koeniginequinone B and their analogues.

Crystal structure of 2-(3,5-dimethoxyphenylamino)-3-chloronaphthalene-1,4-dione

“…The redox polymers based on quinones owing to their redox ability have been investigated to develop batteries and biosensors [17,18]. The title compound which is a substituted-1,4-naphthoquinone containing chloro atom and an arylamine with two methoxy group at m-position has been recently used for the synthesis of biologically and pharmaceutically important carbazolequinone compounds [19]. The structure of the title compound ( Figure 1) was previously elucidated by NMR, IR, and mass spectroscopies and reported [20,21].…”

Hypervalent Iodine(III)‐Mediated Counteranion Controlled Intramolecular Annulation of Exocyclic β‐Enaminone to Carbazolone and Imidazo[1,2‐a]pyridine Synthesis

“…The crude reaction mixture was concentrated under reduced pressure and subsequently purified by silica gel (mesh 60-120) chromatography (50 %e thyl acetate in n-hexane) to afford the desired carbazolone 2a (39.5 mg, 80 %) as aw hite solid;m elting point:2 16-217 8C. The molecule was characterized by 1 H, 13 22.70, 23.40, 37.78, 111.49, 111.73, 120.15, 121.46, 122.38, 124.50, 135.83, 152.25, 192.84 3055, 3032, 29533055, 3032, , 29453055, 3032, , 16013055, 3032, , 14543055, 3032, , 12493055, 3032, , 1176imidazo[1,2-a]pyridin-9(6H)one (3 a);T ypical procedure:A no ven-dried screw-cap reaction vial was charged with 3-(pyridin-2-ylamino)cyclohex-2-enone (50 mg, 0.265 mmol) in dichloroethane (2 mL) as as olvent and then [hydroxy(tosyloxy)iodo]benzene (HTIB) (124.65 mg, 0.318 mmol) and silverhexafluoroantimonate (109.26 mg, 0.318 mmol) were added to the reacting solution. The mixture was stirred for 8h ours at 90 8Ca nd the progress of reaction was monitored by TLC until completion.…”

“…In 2011, Glorius and co‐workers developed a Pd‐catalyzed oxidative coupling of two C−H‐bonds within N ‐arylenamines that allows the efficient formation of differently substituted indoles . In a recent report, He et al., demonstrated a formal [3+2]‐cycloaddition reaction for the synthesis of carbazolequinones through the annulation of aminoquinones with aryne intermediates generated in situ . Moreover, the hypervalent iodine(III) has also been employed to access carbazolones through direct intramolecular N‐arylation reaction .…”

“…[6a, 12] In ar ecent report, He et al,d emonstrated af ormal [3+ +2]-cycloaddition reaction for the synthesis of carbazolequinones through the annulationo fa minoquinones with aryne intermediates generated in situ. [13] Moreover, the hypervalent iodine(III) has also been employedt oa ccess carbazolones through direct intramolecular N-arylation reaction. [14] However, the same strategy failed for the annulation of exocyclic b-enaminones.…”

Transannulation of Pyridotriazoles with Naphthoquinones and Indoles: Synthesis of Benzo[f]Pyrido[1,2‐a]Indoles and Indolizino[3,2‐b]indoles

“…Indolizine derivatives also possess a variety of biological activities such as anti-inflammatory, antiviral, aromatase inhibitory, analgesic, cardiovascular diseases, and HIV infections. [4] Although few synthetic routes have been developed to access pyrido[1,2-a]indole-1,4-dione skeleton, [4][5][6] still there is a great interest to develop new synthetic methods, because the insertion of nitrogen atom into quinone skeleton would change its physicochemical properties and lead to different pharmacophore with a varied biological profile. In the reported protocols, they mostly require at least one leaving group on the quinone moiety for the substitution and elimination.…”