Synthesis of Dibenzosuberones Bearing an Isoxazole Group via Palladium-Catalyzed Intramolecular C-H/C-Br Bond Cross-Coupling of Ortho-Aroylated 3,5-Diarylisoxazoles.

A facile and efficient synthetic methodology for preparing dibenzosuberones via a C-H bond activation strategy is presented. The ortho-aroylated 3,5-diarylisoxazole was employed as the starting substrate to undergo palladium-catalyzed intramolecular C-H/C-Br bond cross-coupling to produce a variety of dibenzosuberones bearing an isoxazole group in 24 to >99% H NMR yields. The dibenzosuberone structure was further confirmed by X-ray crystallography. The developed methodology exhibits very good functional group tolerance. In addition, a rational mechanism was presented for describing the reaction process. For the prepared dibenzosuberone, the use of Mo(CO) as the catalyst can easily transform the isoxazole ring into the β-aminoenone group. Finally, the structure of the anticipated ring-opening product, dibenzosuberenone, bearing a β-amino-α-ketone group was secured by X-ray crystallography.