Transition Metal-Catalyzed Organic Functionalizations Of Azo Compounds

Azo compounds and their derivatives, as the key skeleton of natural products and drug molecules, have been widely applied in many fields of analytical chemistry, materials chemistry and life science. Although great deals of attentions have been focused on transition metal-catalyzed organic functionalizations of azo compounds, the development of simple, efficient, environment-friendly, high selectivity method of synthesis of azo compounds and their derivatives have a very important research value. The thesis mainly focuses on the transition metal-catalyzed organic functionalizations of azo compounds and includes the following three parts.(1) The direct ortho-ethoxycarbonylation of azobenzenes with diethyl azodicarboxylate(DEAD) was developed in the presence of Pd(OAc)2, copper acetate,p-toluenesulfonic acid(p-TsOH) under mild reaction conditions. This transformation proceeded smoothly via C–H bond activation and produced the corresponding ortho-estered azobenzenes in good yields. The approach is simple, efficient and easy operation, which is also applicable to azoxybenzenes.(2) An efficient ortho-acylation of azobenzenes and azoxybenzenes with ?-keto acids has been developed by combining palladium catalysis and visible-light photoredox catalysis at room temperature under 1.5 W blue LED irradiation.Compared with the previous strategy, this approach merged visible-light photocatalysis organic dyes and palladium catalysis of azoxybenzenes, which provided a novel approach to the construction of acyled azoxybenzene.(3) The addition reactions of azobenzenes with DMSO were developed by using Fenton’s reagent as the catalyst under visible-light irradiation. A numbers of N-methylation and N-sulfonylation hydrazine compounds were prepared via N–N bond cleavage of azobenzenes. This approach was occurred at room temperature under mild conditions in the absence of photocatalyst.