Mn‐Mediated Radical Cascade Cyclization of 1,6‐Enynes with Arylboronic Acids to Access Dihydrobenzo[b]fluorenones

Abstract Herein, we report the synthesis of functionalized dihydro‐benzo[ b ]fluorenones through a manganese‐mediated cascade radical cyclization of β ‐alkynyl propenones [1,6‐enynes] with arylboronic acids. In the present strategy, the in‐situ generated aryl radical undergoes chemo‐selective addition followed by 5‐ exo‐trig cyclization. The reaction is emphasized by high atom‐ and step‐economy with the construction of three new C−C bonds to access the dihydrobenzo[ b ]fluorenones in 68–81% yield under mild reaction conditions. The synthetic efficacy of the developed method is evidenced by the construction of new C−C and C−N bonds. magnified image