Ynones as Versatile Electrophiles for the Divergent Synthesis of 4H-Chromenes and 1,4-Dihydroquinolines

Abstract

An efficient and transition-metal-free strategy for the synthesis of 4H-chromenes and 1,4-dihydroquinolines has been developed using 2-hydroxy/2-amino chalcones and ynones as key reaction partners. The transformation proceeds via a sequential oxa- or aza-Michael addition followed by intramolecular cyclization in a cascade manner, affording highly functionalized heterocycles in good to excellent yields. The protocol exhibits broad functional-group tolerance and operational simplicity. Notably, ynones act as dual electrophiles, enabling a unified and divergent approach to two distinct heterocyclic frameworks from closely related precursors, thereby expanding their synthetic utility in heterocycle-oriented synthesis.