Catalyst-free synthesis of diversely substituted 6H-benzo[c]chromenes and 6H-benzo[c]chromen-6-ones in aqueous media under MWI

Abstract

In this paper, a catalyst-free synthesis of diversely substituted 6H-benzo[c]chromenes and 6H-benzo[c]chromen-8-ols via cascade reactions of 2-(2-(allyloxy)phenyl)furan and 2-(2-(prop-2-ynyloxy)phenyl)furan, featured with intramolecular Diels–Alder reactions of furan with unactivated alkene/alkyne in aqueous media under MWI, was developed. In addition, an environmentally friendly oxidation of 6H-benzo[c]chromenes into the corresponding benzo[c]chromen-6-ones using aqueous H₂O₂ as an oxidant, in the absence of any activator/catalyst, was also revealed.