Synthesis Of 1,4-disubstituted Triazoles And Study On Triazole Rings' Palladium Catalyzed C-H Bond Activation Coupling Reaction

1,2,3-Triazoles are important five member N-heterocyclic compounds in organic chemistry due to their inimitable chemical and structural properties, as well as their wide application in pharmaceutical, agrochemicals and industry. Copper catalyzed azide-alkyne cycloaddition reaction is a high selectivity and efficient methord to form 1,4-disubstituted triazoles. Meanwhile, the regioselective preparation of 1,4,5-trisubstituted triazoles still facing lots of challages. Therefor, find a green and efficient way to construct 1,2,3-triazoles is very important. Recently, palladium catalyzed coupling reaction by C–H bond activation has become a hot topic in methodology of organic synthesis. Benefits for low byproduct formed and highly atom economic, this methord has great potential utilized in direct functionalization of unactive aromatic and heterocycles or the formation of new rings.With an emphasis for the synthese of trizoles, this dissertation aims to search for new green and efficient methords mainly contains two parts:(1) Synthesis of 1,4-disubstituted triazoles in scCO2 system. This paper provided an overview of results of organic reactions in scCO2 system in our group. With self-prepared nano CuO, we succeed in synthesing 1,4-disubstituted triazoles with high yields without entrainers. Our methord provides a new solvent-free way of copper catalyze azide-alkyne cycloaddition reaction.(2) 1,4,5-Trisubstituted triazoles were synthesed by activation of C-H bond of triazole rings. Firstly, Pd(II) reactived with C-H bond of triazole rings to then inserted into the alkene to form active intermediate, the target products were formed viaβ-elimination of the active intermediate. We found that the yields were rised when O2 were used as a co-oxidant with Cu(OAc)2. N-monosubstituted triazole was used as an example to demonstrate the regioselective on C-4 or C-5 of the triazole ring. All the products were trans-diastereomer showed the stereoselective of our reation. To the best of our knowledge, this reaction is the first synthesis of 5-alkenylation-1,4,5-trisubstituted triazoles via a C-H activation of triazole rings, casting light on future research for more complicated functionalization of triazoles.