Pd(OAc)₂-Catalyzed C-H Bond Activated Reaction

Pd-catalyzed reaction is one of the most effective methods to systhesize natural organic molecules and a variety of drug molecules, and it is also a siginificant area in organic systhesis. Even though Pd-catalyzed reaction has been deeply developed over the past several decades, it remains to be a huge challenge in organic chemistry. The C-H bond functionalization using Pd11-catalyzed methods has caused extenisve attentions in recent years. Due to the effect of directing groups, this kind of reaction can form the C-C bond, C-N bond, C-0 bond and C-X bond (X=C1, Br, I) etc fromσ-chelation directed C-H bond cleavages. Moreover, this reaction is able to omit several complicated reactions compared with former methods. In this research work, a series of C-H bond functionalizations are able to be conducted via the effects of directing groups in the appearance of Pd(OAc)2 as catalyst:1. Various anilides have been directly ortho-acetoxylated through a Pd(OAc)2-catalyzed C-H bond activation process. The amide group in anilides was found to functionalize as an elegant directing group to convert aromatic sp2 C-H bonds into C-0 bonds in high regioselectivity with acetic acid as the acetate source and K2S2O8 as the oxidant.2. The palladium-catalyzed ortho-alkoxylation of N-methoxybenzamides has been demonstrated. With the CONHOMe group as a directing group, the aromatic C-H bond can be functionalized efficiently to generate ortho-alkoxylated derivatives in moderate to good yields.3. We have developed the synthesis of biologically important phenanthridinones by combining the C-C and C-N bond formation in one pot via the palladium-catalyzed dual C-H activations, which involves four bond ruptures and two bond formations. The utility of the synthesized phenanthridinones is further demonstrated by conversion to other derivatives including natural products.4. The Pd(OAc)2-catalyzed ortho-arylation of benzamides has been realized. Compared with the previous methods, this process which demonstrated the utility of the synthesized phenanthridinones could be performed without any group on the N atom of benzamides.