Diels–Alder reactions of 3-nitro-2 (1H)-quinolones with 1, 3-butadiene derivatives were carried out to give the phenanthridone derivatives under both atmospheric and high pressure conditions. Furthermore, the reactivity of 3-substituted 2 (1H)-quinolones acting as a dienophile with 2, 3-dimethyl-1, 3-butadiene was examined using molecular orbital (MO) calculation.
