Facile and Diverse Synthesis of Benzo[ b]fluorenone Derivatives through a Copper/Selectfluor-Catalyzed Tandem Annulation of 1,6-Enynes.

A facile synthesis of a diverse array of benzo[ b]fluorenone derivatives has been developed. The method involves a Cu⁰/Selectfluor-catalyzed tandem annulation of 1,6-enynes, which takes place under mild reaction conditions. For tert-butylethynyl-substituted 1,6-enynes, the major reaction pathway was a tandem annulation/C-C-bond-cleavage/fluorination process leading to fluorinated benzo[ b]fluorenones as the major products; tert-butyl-substituted benzo[ b]fluorenones were obtained as the minor products. For arylethynyl-substituted 1,6-enynes, the substrates underwent tandem annulations to give 5-aryl-substituted benzo[ b]fluorenones in moderate to excellent yields. For (trimethylsilyl)ethynyl-substituted 1,6-enynes, the reaction involved a tandem annulation/C-Si-bond-cleavage process to deliver 11 H-benzo[ b]fluoren-11-ones in moderate yields. [ABSTRACT FROM AUTHOR]