DOI

  • Ainur D Sharapov
  • Ramil F Fatykhov
  • Igor A Khalymbadzha
  • Maria I Valieva
  • Igor L Nikonov
  • Olga S Taniya
  • Dmitry S Kopchuk
  • Grigory V Zyryanov
  • Anastasya P Potapova
  • Alexander S Novikov
  • Vladimir V Sharutin
  • Oleg N Chupakhin

This paper reports the synthesis of four types of annulated pyranoindole congeners: pyrano[3,2-f]indole, pyrano[2,3-g]indole, pyrano[2,3-f]indole, and pyrano[2,3-e]indole and photophysical studies in this series. The synthesis of pyrano[3,2-f], [2,3-g], and [2,3-e]indoles involve a tandem of Bischler-Möhlau reaction of 3-aminophenol with benzoin to form 6-hydroxy- or 4-hydroxyindole followed by Pechmann condensation of these hydroxyindoles with β-ketoesters. Pyrano[2,3-f]indoles were synthesized through the Nenitzescu reaction of p-benzoquinone and ethyl aminocrotonates and subsequent Pechmann condensation of the obtained 5-hydroxyindole derivatives. Among the pyranoindoles studied, the most promising were pyrano[3,2-f] and [2,3-g]indoles. These compounds were characterized by moderate to high quantum yields (30-89%) and a large (9000-15,000 cm-1) Stokes shift. More detailed photophysical studies were carried out for a series of the most promising derivatives of pyrano[3,2-f] and [2,3-g]indoles to demonstrate their positive solvatochromism, and the data collected was analyzed using Lippert-Mataga equation. Quantum chemical calculations were performed to deepen the knowledge of the absorption and emission properties of pyrano[3,2-f] and [2,3-g]indoles as well as to explain their unusual geometries and electronic structures.

Язык оригиналаанглийский
Номер статьи8867
ЖурналMolecules (Basel, Switzerland)
Том27
Номер выпуска24
DOI
СостояниеОпубликовано - 13 дек 2022

ID: 103128334