Versatile Palladium-catalyzed intramolecular cyclization to access new luminescent azaphosphaphenalene motifs

Chemistry. 2024 Apr 2;30(19):e202303072. doi: 10.1002/chem.202303072. Epub 2024 Feb 19.

Abstract

Using a straightforward sequence of diphosphonylation and a Pd-catalysed concerted-metalation-deprotonation (CMD), a synthetic strategy towards polyaromatic phosphorus containing heterocycles was developed. Herein, we report the synthesis and characterization of new azaphosphaphenalenes, using easily accessible palladium catalysts and starting materials. The key tetrahydroquinoline intermediates of the reaction were synthesised via a fast and effective procedure and could be isolated as such, or further reacted towards the target polyaromatic structures. The obtained products showed interesting luminescent properties and their emission, excitation and quantum yields were evaluated.

Keywords: Cross coupling reaction; Luminescence; Pd-catalysis; Phosphine oxides; Phosphorus; Polyaromatic.