Dual role of polyphosphoric acid-activated nitroalkanes in oxidative peri -annulations: Efficient synthesis of 1,3,6,8-tetraazapyrenes

A highly efficient synthetic method for expeditious and selective assembly of tetraazopyrenes (TAPy) is reported, based on the novel reaction of electrophilically activated nitroalkanes with aromatic amines. Remarkably, the nitroalkanes play a dual role in this process, also serving as mild and efficient oxidants promoting aromatization of the final product and allowing for the exclusion of a poorly controllable aerobic treatment. © 2017 The Royal Society of Chemistry

Unexpected cyclization of 2-(2-aminophenyl)indoles with nitroalkenes to furnish indolo[3,2-: C] quinolines

The polyphosphoric acid-mediated reaction of 2-(2-aminophenyl)indenes with nitroalkenes was tested in the frame of synthetic studies towards CDK inhibitors with the paullone core. Unexpectedly, this reaction proceeded via a different mechanistic pathway affording derivatives of the natural alkaloid isocryptolepine. The scope of this unusual transformation was investigated and a mechanistic rationale explaining this outcome is offered. This journal is © The Royal Society of Chemistry

Improved Method for Preparation of 3-(1H-Indol-3-yl)benzofuran-2(3H)-ones

3-(1H-Indol-3-yl)benzofuran-2(3H)-ones were efficiently accessed via polyphosphoric acid-mediated condensation of 3-(2-nitrovinyl)-1H-indoles with phenols. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Rational design of an efficient one-pot synthesis of 6H-pyrrolo[2,3,4- gh] perimidines in polyphosphoric acid

Several highly efficient one-pot synthetic protocols were developed, enabling polyphosphoric acid-activated nitroalkanes to act as electrophiles in reactions with aminonapthalenes. The featured methods allow for the single step assembly of polyheterocyclic aromatic derivatives of 6H-pyrrolo[2,3,4-gh]perimidine scaffold in high yields. © 2016 The Royal Society of Chemistry

Unexpected cyclization of 2-(2-aminophenyl)indoles with nitroalkenes to furnish indolo[3,2-: C] quinolines

The polyphosphoric acid-mediated reaction of 2-(2-aminophenyl)indenes with nitroalkenes was tested in the frame of synthetic studies towards CDK inhibitors with the paullone core. Unexpectedly, this reaction proceeded via a different mechanistic pathway affording derivatives of the natural alkaloid isocryptolepine. The scope of this unusual transformation was investigated and a mechanistic rationale explaining this outcome is offered. This journal is © The Royal Society of Chemistry

Synthesis of 3,4-dihydroisoquinolines using nitroalkanes in polyphosphoric acid

A new method for the synthesis of 6,7-dimethoxy-3,4-dihydroisoquinoline based on the reaction of 2-(3,4-dimethoxyphenyl)ethan-1-amine (homoveratrylamine) with aliphatic nitro compounds in polyphosphoric acid (PPA) was developed. © 2019, Springer Science+Business Media, Inc

Dual role of polyphosphoric acid-activated nitroalkanes in oxidative peri -annulations: Efficient synthesis of 1,3,6,8-tetraazapyrenes

A highly efficient synthetic method for expeditious and selective assembly of tetraazopyrenes (TAPy) is reported, based on the novel reaction of electrophilically activated nitroalkanes with aromatic amines. Remarkably, the nitroalkanes play a dual role in this process, also serving as mild and efficient oxidants promoting aromatization of the final product and allowing for the exclusion of a poorly controllable aerobic treatment. © 2017 The Royal Society of Chemistry

Direct reductive coupling of indoles to nitrostyrenes en route to (indol-3-yl)acetamides

A highly efficient one-pot method for the reductive coupling of indoles to nitrostyrenes in polyphosphoric acid doped with PCl3 was developed. This method allows direct and expeditious access to primary (indol-3-yl)acetamides, interesting as anti-cancer drug candidates. © 2016 The Royal Society of Chemistry

Michael addition to 3-(2-nitrovinyl)indoles – route toward aliphatic nitro compounds with heterocyclic substituents

[Figure not available: see fulltext.] Synthetic approach toward indole derivatives bearing 2-nitroethyl group and polar azole moiety has been developed. This method involves conjugate addition of 1,3-dicarbonyl compounds to 3-(2-nitrovinyl)-1H-indoles followed by cyclocondensation with hydrazine or hydroxylamine to furnish pyrazole or isoxazole ring. Application of microwave activation allows to obtain the target indole derivatives in short time and avoid protection of indole nitrogen atom. © 2019, Springer Science+Business Media, LLC, part of Springer Nature