Ethoxycarbonyl Substituted Iron Porphyrin Catalyzed Cross-dehydrogenative Coupling Reaction

At present,the construction of iron-catalyzed C-H conversion and C-C bond formation has led to the rapid development of the chemical industry in the past few years.In various ways of constructing C-C bonds,direct coupling of two C-H bonds is the most efficient and environmentally friendly direct method by avoiding the use of organic halides,pseudohalides or organometallic reagents.Thus,two different C-H bonds catalyze direct coupling through transition metal methods have attracted wide attention.Scientists have explored a new method,which is the cross-dehydrogenation coupling reaction(CDC reaction).The CDC reaction is a metal catalyst that directly forms a C-C bond from two different C-H bonds break by a transition under oxidizing conditions.This paper studies the iron-porphyrin catalyzed cross-dehydrogenation coupling reaction of C-O bond formation process.The main contents are as follows:1.TPP,TECP and iron complexes FeTPP,FeTECPCl and Fe-u-OXO were synthesized by "one pot method" at room temperature,and characterized by UV,IR,fluorescence,NMR,cyclic voltammetry,theoretical calculation,mass spectrometry and X-ray single crystal diffraction.2.The catalytic activity of FeTECPCl was better than that of Fe TPP.The catalytic activity of TECP using different metals were studied,FeTECPCl was better than other metal complexes of TECP.The reaction conditions were as follows benzoic acid(0.5 mmol),FeTECPCl(0.5 mol%,relative to benzoic acid),DTBP(1 mmol),1,4-dioxane(1 mL)as substrate and solvent,The reaction was carried out at 120 °C for 4 h as the optimum condition.Under this condition,the yield of the final product was 74%.At the same time,we carried out 30 kinds of substrate development on the substrate,which proved the ethoxycarbonyl iron porphyrin catalyzed cross-dehydrogenation coupling reaction efficiently.Through the whole reaction process,the electron-withdrawing and the electron-donating substrate have good adaptability to this process,and the target product has a relatively high yield.3.In the process of catalytic reaction,we used free radical trapping agent,UV,kinetic isotope effect to explore the mechanism of the reaction.The iron-porphyrin catalyzes the cross-dehydrogenation coupling reaction involved free radicals and undergoes a valence conversion through a single electron transfer mechanism.The reaction of benzoic acid with 1,3-dioxolane has a regioselectivity due to the strong selectivity of the bridging group formation of 1,3-dioxolane.