Polycyclic Indole Derivatives Research Articles

ChemInform Abstract: Fe(OTf)3 Catalyzed Annulation of 2,3‐Disubstituted Indoles with Aziridines.

AbstractFused polycyclic indole derivatives with two consecutive quaternary carbo‐centers are obtained by Fe(O‐Tf)3‐catalyzed [3 + 2] annulation reactions between N‐Tos aziridines and 2,3‐disubstituted indoles.

One-pot approach to 1,2-disubstituted indoles via Cu(II)-catalyzed coupling/cyclization under aerobic conditions and its application for the synthesis of polycyclic indoles.

A straightforward assembly of 1,2-disubstituted indoles has been developed through a Cu(II)-catalyzed domino coupling/cyclization process. Under aerobic conditions, a wide range of 1,2-disubstituted indole derivatives were efficiently and facilely synthesized from 2-alkynylanilines and boronic acids. 2-(2-Bromoaryl)-1-aryl-1H-indoles, which were selectively generated in one pot under the Cu catalysis, afforded the indolo[1,2-f]phenanthridines via Pd-catalyzed intramolecular direct C(sp(2))-H arylation. The one-pot tandem approaches to the polycyclic indole derivatives were also successfully achieved.

Ruthenium‐Catalyzed Intramolecular Allylic Dearomatization/Migration Reaction of Indoles and Pyrroles

AbstractAn efficient synthesis of polycyclic indole and pyrrole derivatives via a ruthenium‐catalyzed intramolecular allylic dearomatization/migration reaction has been developed. This method features wide substrate scope, mild reaction conditions, and an operationally simple procedure. The capture of the spiro intermediate provides solid evidence for the dearomatization/migration reaction pathway.magnified image

ChemInform Abstract: Rhodium(I)‐Catalyzed Cycloisomerization of Nitrogen‐Tethered Indoles and Alkylidenecyclopropanes: Convenient Access to Polycyclic Indole Derivatives.

At the end of its tether: A new synthetic protocol for the preparation of polycyclic indole derivatives has been developed from a rhodium(I)-catalyzed cycloisomerization of a nitrogen-tethered indole and alkylidenecyclopropane, affording the corresponding tetrahydro-β-carboline derivatives in moderate to good yields. Further transformations give a direct and rapid route to tetracyclic compounds through transition-metal catalysis.

Rhodium(I)‐Catalyzed Cycloisomerization of Nitrogen‐Tethered Indoles and Alkylidenecyclopropanes: Convenient Access to Polycyclic Indole Derivatives

At the end of its tether: A new synthetic protocol for the preparation of polycyclic indole derivatives has been developed from a rhodium(I)-catalyzed cycloisomerization of a nitrogen-tethered indole and alkylidenecyclopropane, affording the corresponding tetrahydro-β-carboline derivatives in moderate to good yields. Further transformations give a direct and rapid route to tetracyclic compounds through transition-metal catalysis.

Copper-catalyzed domino intramolecular cyclization: a facile and efficient approach to polycyclic indole derivatives

A mild and efficient Cu(2)O-catalyzed domino intramolecular C-N coupling/C-Y (Y = O, S, N) bond formation was successfully achieved. Thus oxazino[3,2-a]indole, thiazino[3,2-a]indole and indolo[2,1-b]quinazoline derivatives were facilely assembled from readily accessible gem-dibromovinyl systems. The protocol is general and practical, affording a variety of the indole-incorporated products in good to excellent yields even under air atmosphere.

Unexpected formation of fluorine-containing tetrahydrocarbazole during the reaction of indole, paraformaldehyde, and fluorine-containing β-ketoesters

A surprise and mild method to prepare fluorine-containing indole derivatives through a one-pot three-component condensation reaction sequence is presented. To our surprise, during the reaction of preparation of fluorine-containing indole derivatives, unexpected formation of fluorine-containing tetrahydrocarbazole was found. Moreover, this method has been demonstrated in the preparation of functionalized polycyclic indole derivatives in a straightforward and atom-economical manner.

An efficient synthesis of fused polycyclic indole derivatives via Aldol-Hetero Diels-Alder reaction of α,β-Unsaturated Thio-oxindoles with various dienophiles

An efficient and one-pot synthesis of thiopyrano[2,3-b]indole derivatives via Hetero Diels-Alder reaction of α,β-Unsaturated thio-oxindoles with electron poor acetylenes and Cyclic Dienophiles is described. In the proposed method the reaction is performed under neutral and one-pot reaction conditions, and also the substances can be mixed without any activation or modification and without using any catalysts.

Synthesis of Novel Polycyclic Indole‐Annulated Thiopyranocoumarin Derivatives via Domino Knoevenagel–Hetero‐Diels–Alder Reaction in Aqueous Media

AbstractAn efficient synthesis of polycyclic indole derivatives is achieved via domino Knoevenagel–hetero‐Diels–Alder reaction of O‐acrylated salicylaldehyde derivatives with dihydroindole‐2‐thiones in H2O as solvent. The products are formed in good‐to‐excellent yields with high regio‐ and stereoselectivity.

Palladium-Catalyzed Synthesis of Fused Heterocycles

The synthesis of fused polycyclic indole derivatives under palladium catalysis is described. Tetracyclic indenones 2 (R¹-R² = benzo) were prepared from diaryl ketones 1 in high yield via an intramolecular arylation process. Unprotected (X = NH) and protected (X = NMe, NPh) indoles were found to participate equally well in the reaction. Examples using furan and thiophene substrates were also presented. Performing the same reaction in the presence of an alkyne 4 gave the tetracyclic products 5 incorporating a fused seven-membered ring. A variety of symmetrical and unsymmetrical alkynes bearing EDGs and EWGs were well tolerated in the reaction. In all cases only a single regioisomer was observed. A plausible mechanism is presented by analogy to that proposed by Larock for similar processes (R. C. Larock et al. J. Org. Chem. 1997, 62, 7536).

ChemInform Abstract: Single and Consecutive Cyclization Reactions of Alkynyl Carbene Complexes and 8‐Azaheptafulvenes: Direct Access to Polycyclic Pyrrole and Indole Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Single and Consecutive Cyclization Reactions of Alkynyl Carbene Complexes and 8‐Azaheptafulvenes: Direct Access to Polycyclic Pyrrole and Indole Derivatives

The reactivity of alkynyl and enynyl Fischer carbene complexes towards 8-azaheptafulvenes is examined. Alkynyl carbenes 1 a-f undergo regioselective [8+2] heterocyclization with 8-aryl-8-azaheptafulvenes 2 a, b providing cycloheptapyrroles 3 and 4 with metal carbene or ester functionality at C3. Moreover, consecutive cyclization reactions are involved when enynyl carbenes are used. Thus, the cyclopenta[b]pyrrole framework 7 is formed by the consecutive [8+2] cyclization and cyclopentannulation reactions. The initially formed cyclopentannulation adduct can be intercepted through a Diels-Alder reaction with classic dienophiles to afford increasing structural complexity (compounds 8 and 9). More importantly, the construction of the indole skeleton is accomplished with a high degree of substitution and functionalization (compounds 11-15) by a one-pot sequence that involves [8+2] cyclization, R--NC or CO insertion, and ring closure.

Trisoxazoline/Cu(II)-catalyzed asymmetric intramolecular Friedel–Crafts alkylation reaction of indoles

Intramolecular Friedel–Crafts alkylation reaction of indoles catalyzed by trisoxazoline/copper(II) is described. This annulation provides an easy access to polycyclic indole derivatives with up to 90% ee in up to 99% yield.

ChemInform Abstract: Synthesis of Polycyclic Indole Derivatives from 2,4,6‐Trinitrotoluene.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Flexible, Convergent Approach to Polycyclic Indole Structures: Formal Synthesis of (±)-Mersicarpine

The formal synthesis of (+/-)-mersicarpine was achieved using an intermolecular radical addition-radical cyclization cascade. This key reaction represents a flexible, convergent route to numerous polycyclic indole derivatives.

Synthesis of polycyclic indole derivatives from 2,4,6-trinitrotoluene

Polycyclic indole derivatives of imidazole and pyrazine series with previously unknown combination of substituents, as well as representatives of the new heterocyclic systems of triazole and furoxan series, were synthesized on the basis of 2-aryl-4-isobutylsulfonyl-6-nitroindoles – products of 2,4,6-trinitrotoluene transformations.

Synthesis of N‐Fused Tricyclic Indoles by a Tandem [1,2] Stevens‐Type Rearrangement/1,2‐Alkyl Migration of Metal‐Containing Ammonium Ylides

An alkyne moiety is activated efficiently with a [W(CO)6] or [ReBr(CO)5] catalyst in the presence of an amine functionality in the title reaction of N-(2-alkynylphenyl)amines. The resulting ammonium ylides undergo rearrangement to form a variety of N-fused polycyclic indole derivatives (see scheme; n=1,2; R=alkyl, Ph).

A New Entry to Polycyclic Indole Derivatives via Intramolecular Imino Diels−Alder Reaction: Observation of Unexpected Reaction

A new, efficient, and highly diastereoselective synthesis of polycyclic indole derivatives through intramolecular imino Diels-Alder reaction of aminoanthraquinone with N-prenylated indole-2-carboxaldehydes in the presence of 20 mol % of triphenylphosphonium perchlorate (TPPP) is reported with extremely high cis selectivity in good yield.

Scope and Mechanism of the PdII‐Catalyzed Arylation/Carboalkoxylation of Unactivated Olefins with Indoles

Treatment of 1-methyl-2-(4-pentenyl)indole (5) with a catalytic amount of [PdCl2(MeCN)2] (2; 5 mol %) and a stoichiometric amount of CuCl2 (3 equiv) in methanol under CO (1 atm) at room temperature for 30 min gives methyl (9-methyl-2,3,4,9-tetrahydro-4-carbazolyl)acetate (6), which was isolated in 83% yield. A number of 2- and 3-alkenyl indoles undergo a similar palladium-catalyzed cyclization/carboalkoxylation to give the corresponding polycyclic indole derivatives in moderate to excellent yields with excellent regio- and diastereoselectivity. Under similar conditions, vinyl arenes undergo intermolecular arylation/carboalkoxylation with indoles to give 3-(1-aryl-2-carbomethoxyethyl) indoles in moderate yield with high regioselectivity. Stereochemical analyses of the palladium-catalyzed cyclization/carboalkoxylation of both 2- and 3-alkenyl indoles are in agreement with mechanisms involving outer-sphere attack of the indole on a palladium-olefin complex followed by alpha-migratory insertion of CO and methanolysis of the resulting acyl palladium intermediate. CuCl2 functions as the terminal oxidant in this palladium-catalyzed cyclization/carboalkoxylation of alkenyl indoles and also significantly increases the rate of reaction of 2 with the alkenyl indole to form the corresponding acyl palladium complex. Spectroscopic studies are in agreement with the intermediacy of a heterobimetallic Pd/Cu complex as the active catalyst in this reaction.

A Facile Method for the Synthesis of Polycyclic Indole Derivatives: The Generation and Reaction of Tungsten‐Containing Azomethine Ylides.

AbstractFor Abstract see ChemInform Abstract in Full Text.