Efficient Synthesis of Chromeno[4,3,2‐de] [1,6]naphthyridine Derivatives via Pseudo Four‐Component Reaction

Abstract A novel approach to the synthesis of substituted 5‐amino‐4‐cyanochromeno[4,3,2‐ de ][1,6]naphthyridine‐1‐carboxylates from a wide range of substituted 2‐hydroxybenzaldehydes with alkyl 3‐oxo‐3‐substituted propanoates and malononitrile was investigated via propionic acid‐promoted cascade Knoevenagel condensation/Michael addition/intramolecularly nucleophilic addition accompanied by oxidative aromatization. This procedure provided a highly efficient and facile route to functionalized chromenonaphthyridines from readily available substrates under mild reaction conditions.