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

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. A novel strategy for the assembly of a wide range of structurally diverse, sophisticated [5,6,5]-oxygen-containing tricyclic frameworks is developed through bismuth(III) trifluoro-methanesulfonate-catalyzed [3+2] annulation protocol. Moderate-to-excellent yields are observed among different propargylic alcohols and 2-allylphenols, providing a practical approach for accessing oxygen-containing tricyclic skeletons, which exhibit anti-tumor activities against three types of human cancer cell lines. image