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

Abstract

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 crosscoupling to produce a variety of dibenzosuberones bearing an isoxazole group in 24 to >99% 1 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) 6 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.

Investigation of Stepwise and Stoichiometric Palladium-Mediated ortho-C–H Bond Arylation and Alkylation of 9(10H)-Acridinone

“…In view of this, the straightforward modification of the 9­(10 H )-acridinone skeleton at a specific position would enable simpler and more efficient derivatizations. In the past decade, transition-metal-catalyzed C–H bond activation/functionalization has received a lot of research attention. , This synthetic strategy can greatly reduce the reaction steps and reagents used, leading to more efficient synthesis. Meanwhile, the combination of the directing group (DG) and transition metal in organic synthesis can selectively activate and functionalize a specific C–H bond, such as ortho, meta, and para positions of a benzene ring .…”

Transition Metal‐Mediated Functionalization of Isoxazoles: A Review

“…[29] In 2020, Chu and co-workers efficiently synthesised isoxazoles bearing dibenzosuberenone analogues by a Pd-catalyzed intramolecular CÀ H/CÀ Br bond cross-coupling of ortho-aroylated 3,5-diarylisoxazoles (Scheme 20). [30] The authors successfully cleaved the isoxazole ring using Mo(CO) 6 and converted it into β-aminoenone group which is susceptible for further synthetic modifications.…”