Facile One-Pot Synthesis of Functionalized Quinoline-Fused Fluorescent Dihydro/Spiro-quinazolinone Derivatives

A facile and efficient method has been developed for the synthesis of quinoline-fused fluorescent dihydro/spiroquinazolinones. A plausible mechanism involving an acid-mediated enaminone intermediate is provided. The reaction proceeded using p-toluene sulfonic acid as a green promoter. The methodology was successful in synthesizing various quinoline-appended spiro-quinazolinones 4a-o. The synthetic utility of compounds 4a-o was demonstrated by synthesizing compounds 6a-d via Suzuki coupling as a key reaction. Significantly, the pi-pi* electronic transition of compounds 4c and 4k showed a blue shift. The molar extinction coefficient (epsilon), Stoke's shift (Delta(u) over bar), and quantum yield (Phi(f))(c) were calculated for these derivatives (4c and 4k).