One-pot assembly of large heterocyclic quinones through three-component reactions

Treatment of indoles with 2,5,8-quinolinetriones in the presence of a catalytic amount of hydrochloric acid afforded heptacyclic reaction products arising from a cascade of two regioselective Michael addition–Diels–Alder cycloaddition steps. In another approach to polyheterocyclic quinone systems, double Diels–Alder reactions between indolylquinolinetriones and 2,5- or 2,6-dihalogenated benzoquinones provided regioisomeric 11-cycle products in good yields.