Lewis Acid‐Catalyzed Tandem Annulation of Propargylic Alcohols with 2‐Allylphenols and Their Anti‐tumor Activities

Abstract A novel bismuth(III) trifluoro‐methanesulfonate‐catalyzed and environmentally benign synthetic strategy for the construction of a wide range of structurally diverse, sophisticated [5,6,5]‐oxygen‐containing tricyclic frameworks with easy‐to handle propargylic alcohols and 2‐allylphenols as substrates in the presence of Bi(OTf) 3 and AgOTf is described. This Lewis acid catalyzed [3+2] annulation protocol, which tolerates a great deal of functional groups, proceeds through a sequential Meyer‐Schuster rearrangement, nucleophilic substitution, 5‐ exo ‐trig cyclization, 5‐ endo ‐trig cyclization, and proton exchange sequences, affording a versatile approach for accessing oxygen‐containing tricyclic skeletons in moderate‐to‐excellent yields. In addition, most of the obtained compounds exhibited anti‐tumor activities against three types of human cancer cell lines in vitro , including Caco‐2 colon cancer cells, MCF‐7 breast cancer cells, and Hepg‐2 liver cancer cells.