Palladium - Catalyzed Oxidation Of The Sp_2 Hydrogen - Bonded Oxidative Functionalization Reaction

In the last decade, transition-metal-catalyzed C-H bond functionalization protocols have emerged as a valuable and atom-economical alternative to traditional cross-couplings in the construction of carbon-carbon and carbon-heteroatom bonds. This paper mainly introduced two kinds of new C-H activation reactions:palladium catalyzed direct ortho-acylation through an oxidative coupling of acetanilides with toluene derivatives and palladium-catalyzed direct ortho-alkoxylation of aromatic azo compounds with alcohols.In numerous strongly or weakly coordinating directing groups, acylamino group was noticeable. Using acylamino as a directing group, ortho C-H bond of acetanilide could be highly regioselectively functionalized. we have developed an efficient method for the direct ortho-acylation of acetanilides via a Pd-catalyzed directed sp2C-H bond activation. Low toxic, stable and commercially available toluene derivatives were used as acyl sources, and inexpensive, safe, and environmentally benign TBHP was employed to be an effective oxidant in these transformations. The reaction exhibited good functional group tolerance. The mild reaction conditions provide future opportunities to apply this methodology in the synthesis of natural products and other useful compounds.Next, we have developed an efficient route for direct alkoxylation of aromatic azo compounds via a Pd-catalyzed azo group directed sp2C-H bond activation, in which PhI(OAc)2was found to be a particularly effective oxidant to these transformations and exhibited functional group tolerance. A series of azobenzene derivatives with either electron-donating or electron-withdrawing groups could be alkoxylated directly and efficiently. The method was applicable to both primary and secondary alcohols. This work provided a convenient method for the syntheses of2-alkoxyl aromatic azo compounds and therefore is an important extension of the chemistry of azo compounds.