Synthesis of New 2-Vinylation Products of Indole via a Michael-Type Addition Reaction with Dimethyl Acetylenedicarboxylate and Their Diels−Alder Reactivity as Precursors of New Carbazoles

Access to 5-Methyl-5H-naphtho[2,3-c]carbazole-8,13-dione Derivatives via Copper-Catalyzed Intramolecular Isomerization

Carbazole-fused quinones are important compounds for their potential pharmacological activities and photophysical properties. Here, a novel copper-catalyzed intramolecular isomerization process to access a new class of naphtho[2,3-c]carbazole-8,13-dione derivatives via a furan isomerization/γ-H elimination and β-C elimination/6π-electrocyclization/aromatization cascade is reported. Furthermore, the preliminary photophysical properties of the functional 5-methyl-5H-naphtho[2,3-c]carbazole-8,13-dione derivatives have been studied.

B(C6F5)3-Catalyzed [4 + 2] Cyclization Strategy: Synthesis and Photophysical Properties of 5H-Naphtho[2,3-c]carbazole-8,13-dione Derivatives

In this paper, a series of novel carbazolequinones were efficiently obtained by a B(C₆F₅)₃-catalyzed [4 + 2] cyclization reaction. This protocol not only had a simple operation, broad substrate range, and high atomic economy, but also had a low catalyst loading and avoided using metal catalysts. In addition, we constructed diverse new carbazole-fused compounds under different reduction conditions. The results of photophysical characterization showed that the structure of carbazole-fused derivatives had a significant impact on the fluorescence properties.

Chemistry of 2-Vinylindoles: Synthesis and Applications

As a class of compounds, 2-vinylindoles have demonstrated a wide range of biological properties. Due to the general interest in these synthons, new divergent protocols of chemical synthesis have been...

Domino Reaction of Aromatic Aldehydes and 1,3-Indanediones for Construction of Bicyclo[2.2.2]octanes and Dibenzo[b,g]indeno[1',2':3,4]fluoreno[1,2-d]oxonines

Triethylamine promoted the pseudo-five-component reaction of aromatic aldehyde with four molecules of 1,3-indanediones in refluxing ethanol to give unique polycyclic bicyclo[2.2.2]octane derivatives containing bridged- and spiro-indanone scaffolds in good yields. The mechanistic studies supported that the reaction included base-catalyzed cyclotrimerization of 1,3-indanedione to give an active cyclic diene and the sequential Diels-Alder reaction with in situ generated 2-arylidene-1,3-indanediones as electron-deficient dienophiles. On the other hand, the pseudo-four-component reaction of salicylaldehyde with 1,3-indanedione afforded the dibenzo[b,g]indeno[1',2':3,4]fluoreno[1,2-d]oxonines in high yields. This reaction clearly demonstrated the high efficiency, molecular convergence, atom-economy, and impressive selectivity of multicomponent reactions.

Protocols for the Syntheses of 2,2'-Bis(indolyl)arylmethanes, 2-Benzylated Indoles, and 5,7-Dihydroindolo[2,3-b]carbazoles

The electrophilic substitution reaction of 4,7-dihydroindole with aryl-aldehydes as an electrophilic partner followed by an oxidation step to deliver 2,2'-bis(indolyl)arylmethanes was studied for the first time. The reaction afforded regioselectivity at the 2,2'-positions of indole in an operationally simple and inexpensive procedure with a variety of substrates. To the best of our knowledge, this is the first set of examples of 2,2'-bis(indolyl)arylmethanes obtained in a substituent-free manner. A facile method from dipyrromethanes to the corresponding 2-benzylindoles was also reported. In addition, 2,2'-bis(indolyl)arylmethanes were converted to 5,7-dihydroindolo[2,3-b]carbazoles.

Bismuth nitrate-promoted disproportionative condensation of indoles with cyclohexanone: a new-type azafulvenium reactivity of indole

The bismuth nitrate-promoted disproportionative condensation of indoles with cyclohexanone in one pot, to yield C3-cyclohexyl substituted indoles and 1,3-di(1H-indol-3-yl)benzene derivatives is reported for the first time.

A facile one-pot method to synthesise 2-alkylated indole and 2,2′-bis(indolyl)methane derivatives using ketones as electrophiles and their anion sensing ability

Indole derivatives are of great importance because of their biological activity and application in technology.

Silver catalyzed domino aza-annulation/Diels–Alder cyclization of 2-ene-yne anilines: a facile one-pot access to carbazole, dihydrocarbazole and tetrahydrocarbazole frameworks

AgSbF₆-catalyzed domino aza-annulation/Diels–Alder/aromatization cascade for the construction of carbazoles, dihydrocarbazoles, tetrahydrocarbazoles and 3-indolyl-substituted tetrahydrocarbazoles was achieved.

Synthesis of benzimidazole[2.1-b][1,3]oxazine spirooxindoles via three-component reaction of N-benzylbenzimidazole, acetylenedicarboxylates, and N-alkylisatins

The three-component reaction of N-benzylbenzimidazole, dialkyl acetylenedicarboxylate, and N-alkylisatins in tetrahydrofuran at room temperature afforded the novel functionalized benzimidazole[2.1-b][1,3]oxazine spirooxindoles in good yields. (1)H NMR spectra indicated that two diastereoisomers with a ratio of 1:3-1:6 exist in the obtained spirooxindole derivatives.

Synthesis of 3,4-dihydropyridin-2(1H)-ones and 3,4-dihydro-2H-pyrans via Four-component reactions of aromatic aldehydes, cyclic 1,3-carbonyls, arylamines, and dimethyl acetylenedicarboxylate

A protocol has been developed for the efficient synthesis of structurally diverse 3,4-dihydropyridin-2(1H)-ones and 3,4-dihydro-2H-pyrans via four-component reactions of arylamines, acetylenedicarboxylate, aromatic aldehydes and cyclic 1,3-diketones. The selective formation of the very different pyridinone or pyran derivatives depends on the structure of cyclic 1,3-diketone. The key steps are proposed to involve Michael addition of the enamino ester formed in situ from the reaction of arylamine with dimethyl acetylenedicarboxylate to arylidine cyclic 1,3-diketones.

A Simple Synthesis of N-Vinylpyrrole, N-vinylindole and N-Vinylcarbazole Derivatives

Reaction of pyrrole, indole or carbazole with dialkyl acetylenedicarboxylates catalysed by N-methylimidazole provides a simple and efficient route for the synthesis of N-vinylpyrrole, N-vinylindole and N-vinylcarbazole derivatives in high yields.

Chiral Brønsted acid catalyzed Friedel-Crafts alkylation reactions

The asymmetric Friedel-Crafts reaction is one of the most powerful methods to synthesize optically active aromatic compounds. Particularly, the Friedel-Crafts alkylation of arenes with unsaturated compounds activated by chiral Brønsted acids provides direct access to enantiopure aromatic derivatives with perfect atom economy. In this tutorial review, recent progress in the development of chiral Brønsted acid-catalyzed asymmetric Friedel-Crafts reactions is presented.