Conjugated heterocumulenes. Synthesis of conjugated carbodiimides and their facile conversion via intramolecular cycloaddition into nitrogen heterocycles, quinoline and pyrido[2,3-b]indole (α-carboline) derivatives

Abstract
A convenient method is described for the synthesis of conjugated carbodiimides and their application to nitrogen heterocycle synthesis via electrocyclisation–intramolecular Diels–Alder reaction.