Ultrasound‐Assisted Multi‐Component Synthesis of New Polysubstituted Quinolino‐Chromene Analogues

ABSTRACT A simple, versatile, ultrasound‐assisted one‐pot multi‐component approach is reported for the preparation of polyfunctionalised quinolino‐chromene compounds from 2‐naphthol, malononitrile and various substituted benzaldehydes and quinoline aldehydes in ethanol in the presence of triethylamine as a base catalyst. The ultrasound‐assisted reaction is efficient and leads to the formation of a range of compounds (4a‐k) with good to excellent yields (70%–97%) in a relatively short time. The compounds were characterised by IR, 1 H NMR, 13 C NMR, 15 N NMR, and high‐resolution mass spectrometry (HRMS). The enhancement in the reaction rate can be ascribed to the influence of ultrasound in facilitating mass transfer. Although ethanol is a relatively safe solvent, triethylamine was used, which suggests that the method is not entirely green. Nevertheless, the protocol provides a convenient strategy to access a range of structurally varied chromene‐based heterocyclic compounds that could be of potential interest in the pharmaceutical industry.