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/spiro-quinazolinones. 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 π-π* electronic transition of compounds 4c and 4k showed a blue shift. The molar extinction coefficient (ε), Stoke's shift (Δ u̅ ), and quantum yield (Φ f ) c were calculated for these derivatives ( 4c and 4k ).