Palladium-catalyzed cascade reactions in aqueous media: synthesis and photophysical properties of pyrazino-fused quinazolinones

Abstract

Heterocycle-fused quinazolinone derivatives have attracted great attention due to their diversified biological and optical activities. In this study, a novel one-pot palladium-catalyzed cascade C–C coupling/cyclization/aromatization of 2-(4-oxoquinazolin-3(4H)-yl)acetonitrile derivatives with arylboronic acids has been disclosed to synthesize 1,3-diaryl-6H-pyrazino[2,1-b]quinazolin-6-one in water. This protocol provides an efficient access to valuable pyrazino-fused quinazolinones in a green solvent (i.e., water) with yields ranging from moderate to excellent. Furthermore, the photophysical properties of these molecules were investigated. The resultant pyrazino-fused quinazolinones exhibit tunable fluorescence, and 3e displays the aggregation induced emission properties with a large Stokes shift. This study provides a useful approach to the development of pyrazino-fused quinazolinones, which have potential applications in chemistry, biology, and materials science.