Synthesis of Carbazoles via an Intramolecular Cyclization of 2-(6-Substituted 3(Z)-hexen-1,5-diynyl)anilines and Their Related Molecules

Unsaturated Four-Membered Rings: Efficient Strategies for the Construction of Cyclobutenes and Alkylidenecyclobutanes

Our recent studies of the diastereo- and enantioselective formation of strained alkylidenecycloalkanes drove us to more-thoroughly investigate the formation of four-membered rings for which only few efficient methods are described. We first developed a strategy to diversify the saturated part of the four-membered ring and applied it to a highly diastereoselective synthesis of more-elaborate alkylidenecyclobutanes, which completed our precedent studies. In parallel, cyclobutene structures were built employing simple organometallic methods and further functionalized to give a diverse range of new substitution patterns, which consequently enriched the pool of cyclobutene-based building blocks.

Gold(i)-catalysed cascade reactions in the synthesis of 2,3-fused indole derivatives

Unactivated alkenes and 1,3-unsubstituted indoles in gold(i)-catalysed hydroaminative/arylative cascade cyclizations.

One-pot synthesis of 1,3-enynes with a CF3 group on the terminal sp2 carbon by an oxidative Sonogashira cross-coupling reaction

One-pot synthesis of 1,3-enynes with a CF₃ group on the terminal sp² carbon was achieved by an oxidative Sonogashira cross-coupling reaction with (E)-trimethyl(3,3,3-trifluoroprop-1-enyl)silane.

Insight into Pd-catalyzed branching cyclizations of enediyne-imides towards furo[2,3-b]pyridines: a DFT study

The DFT mechanisms for Pd-catalyzed branching cyclizations of cross-conjugated enediyne-imides towards furo[2,3-b]pyridines have been investigated to discover the crucial factors of controlling the chemo- and solvent-directed product selectivity.

Solvent-free synthesis of heteroannulated carbazoles: a novel class of anti-tumor agents

A series of novel carbazole analogues that hold pyrido, isoxazolo, pyrimido and pyrazolo templates were designed and synthesised in good yield by grinding conditions. All the synthesised compounds were screened for their anti-tumor activity and displayed enviable selective growth inhibition on HeLa cell line compared to AGS cell line. Among these compounds, compound 2-(3',4'-diethoxy-benzylidene)-6-methyl-2,3,4,9-tetrahydro-carbazol-1-one,6-chloro-2-(3',4'-diethoxy-benzylidene)-2,3,4,9-tetrahydro-carbazol-1one, 2-(3',4'-diethoxy-benzylidene)-8-methyl-2,3,4,9-tetrahydro-carbazol-1-one, 3-(3',4'-diethoxyphenyl)-7-methyl-4,5-dihydro-10H-isoxazolo[3,4-a]carbazole, 7-chloro-3-(3',4'-diethoxyphenyl)-4,5-dihydro-10H-isoxazolo[3,4-a]carbazole, 4-(3',4'-diethoxyphenyl)-2-ethoxy-8-methyl-6,11-dihydro-5H-pyrido[2,3-a]carbazole-3-nitrile, 8-chloro-4-(3',4'-diethoxyphenyl)-2-ethoxy-6,11-dihydro-5H-pyrido[2,3-a]carbazole-3-nitrile, 4-(3',4'-diethoxyphenyl)-2-ethoxy-10-methyl-6,11-dihydro-5H-pyrido[2,3-a]carbazole-3-nitrile were found to have promising anti-tumor properities with reference to the standard ellipticine against the HeLa cancer cell line. All these intermediates showed IC50 outranged the standard ellipticine. The same compounds showed moderate activity against AGS cancer cell lines. The efforts were undertaken to optimize potency and selectivity of this class of compounds.

Recent advances in the benzannulation of substituted 3-alkoxycarbonyl-3,5-hexadienoic acids and 3-alkoxycarbonylhex-3-en-5-ynoic acids to polysubstituted aromatics

The benzannulation reactions of substituted 3-alkoxycarbonyl-3,5-hexadienoic and 3-alkoxycarbonylhex-3-en-5-ynoic acids offer a straightforward access to various polysubstituted aromatic compounds. The process is very flexible, and can be applied to the regiospecific preparation of oligoaryls, naphthalenes, ring-fused heterocycles, chiral tetrahydronaphthalenes, C-aryl-glycosides and many natural products of different structure. In this Concept article, we highlight the potential of this annulation reaction by illustration of our recent contribution to this field, as well as the studies previous reported by others.

Synthesis of Carbazoles and Dibenzofurans via Cross-Coupling of o-Iodoanilines and o-Iodophenols with Silylaryl Triflates and Subsequent Pd-Catalyzed Cyclization

An efficient route to a variety of carbazoles and dibenzofurans has been developed. It involves the reaction of o-iodoanilines or o-iodophenols with silylaryl triflates in the presence of CsF to afford the N- or O-arylated products, which are subsequently cyclized using a Pd catalyst to carbazoles and dibenzofurans in good to excellent yields. By using this methodology, the carbazole alkaloid mukonine has been synthesized in 76% overall yield in three steps.

Gold-Catalyzed Reactions of 2-Alkynyl-phenylamines with α,β-Enones

[reaction: see text] The gold-catalyzed reaction of 2-alkynyl-phenylamines with alpha,beta-enones represents a new general one-pot entry into C-3-alkyl-indoles by sequential reactions. Gold-catalyzed sequential cyclization/alkylation, N-alkylation/cyclization, or N-alkylation/cyclization/alkylation reactions leading to different indoles can be directed by changing the 2-alkynyl-phenylamine 1/alpha,beta-enone 3 ratio and the reaction temperature. Unusual gold-catalyzed rearrangement reaction of indoles are observed at 140 degrees C. New gold-catalyzed formation of propargyl-alkyl ether under mild conditions and the hydration reaction of N-acetyl-2-ethynyl-phenylamine are reported.