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

ABSTRACT

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-4H-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.