3-Alkynylindoles as Building Blocks for the Synthesis of Electronically Tunable Indole-Based Push-Pull Chromophores.


ERDEN K., DENGİZ Ç.

The Journal of organic chemistry, vol.87, no.6, pp.4385-4399, 2022 (Peer-Reviewed Journal) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 87 Issue: 6
  • Publication Date: 2022
  • Doi Number: 10.1021/acs.joc.2c00067
  • Journal Name: The Journal of organic chemistry
  • Journal Indexes: Science Citation Index Expanded, Scopus, Academic Search Premier, BIOSIS, Chemical Abstracts Core, Chimica, Compendex, EMBASE, MEDLINE, Index Chemicus (IC)
  • Page Numbers: pp.4385-4399

Abstract

© 2022 American Chemical Society.In this study, two different classes of push-pull chromophores were synthesized in modest to excellent yields by formal [2+2] cycloaddition-retroelectrocyclization (CA-RE) reactions. N-Methyl indole was introduced as a new donor group to activate alkynes in the CA-RE transformations. Depending on the side groups' size and donor/acceptor characteristics, N-methyl indole-containing compounds exhibited λmax values ranging between 378 and 658 nm. The optoelectronic properties of the reported D-A-type structures were studied by UV/vis spectroscopy and computational studies. The complete regioselectivity observed in the products was elaborated by one-dimensional (1D) and two-dimensional (2D) NMR studies, and the electron donor strength order of N-alkyl indole and triazene donor groups was also established. The intramolecular charge-transfer characteristics of the target push-pull chromophores were investigated by frontier orbital depictions, electrostatic potential maps, and time-dependent density functional theory calculations. Overall, the computational and experimental results match each other. Integrating a new donor group, N-alkyl indole, into the substrates used in formal [2+2] cycloaddition-retroelectrocyclizations has significant potential to overcome the limited donor-substituted substrate scope problem of CA-RE reactions.