A Versatile Pd-Catalyzed Alkyne Annulation Process for Benzo[ a ]carbazoles and their Anticancer Analogues.

A Pd-catalyzed, simple, and divergent approach for the direct synthesis of benzo[ a ]carbazoles from internal alkynes and N -tosyl-iodoindoles has been demonstrated. This methodology highlights the influences of reaction media and temperature for the synthesis of either N-protected or N-deprotected benzo[ a ]carbazoles. This cascade strategy provides a series of electronically different benzo[ a ]carbazoles with good yields. The synthesized benzo[ a ]carbazoles were evaluated for in vitro anticancer activity against human lung cancer A549 cells and human breast cancer MDA-MB-231 cells. Notably, two of the representative analogues displayed potent anticancer activity against both cancer cell lines.