Synthesis of 6-Benzo[c]chromene Scaffolds: A Synthetic Strategy of Pd-Catalyzed Annulation Followed by Aerial Oxidation.

A synthetic strategy of a palladium-catalyzed cascade annulation reaction followed by aerial oxidation was designed to construct 6-benzo[c]chromene scaffolds. Various 6-benzo[c]chromenes were synthesized under mild reaction conditions using easily accessible -QMs and commercially available -hydroxyarylboronic acids. One of the synthesized chromenes has been ambiguously confirmed by single-crystal XRD analysis. Interestingly, our synthesized 6-benzo[c]chromenes could be easily transformed into valuable 6-benzo[c]chromen-6-ones via aerial oxidation.