Synthesis of N-Heteropolycyclic Compounds Including Quinazolinone Skeleton Using Friedel–Crafts Alkylation

A simple method to synthesize N-heteropolycyclic quinazolinones was developed including Knoevenagel condensation of quinazolines and aldehydes and Friedel–Craft alkylation as key steps. Knoevenagel reaction of 2-methyl-3-phenylquinazolin-4(3H)-one proceeded smoothly under a basic condition and subsequent Friedel–Craft alkylation with Brønsted acid gave the N-heteropolycyclic quinazolinones in good yields. Furthermore, these new polycyclic compounds were converted into organic molecules having a long π-conjugation system by treatment of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) to utilize them as organic dyes.