Synthesis of 4-aryl-3,4-dihydrocoumarins and 4-aryl-4 H -chromenes via Er(OTf) 3 -catalyzed cascade reactions of p -quinone methides with 1,3-dicarbonyl compounds.

The Er(OTf) 3 -catalyzed cascade cyclization reaction of para -quinone methides ( p -QMs) with various 1,3-dicarbonyl compounds has been developed, which efficiently constructed a series of versatile 4-aryl-3,4-dihydrocoumarins and 4-aryl-4 H -chromenes. Herein, we not only propose a novel cyclization strategy of p -QMs, but also provide an easy access to structurally diverse coumarins and chromenes.