Study On Application Of Indazoliums Halide In Pd-catalyzed Suzuki-miyaura Cross-coupling And Rearrangement

Biaryls are important structural motifs and have a high status in the field of fine chemicals, pharmaceuticals and material science. Cross-coupling of arylmetal reagents with aryl halides is a fundamentally important process that represents one of the most straightforward ways to access biaryls in high yields. Among them, owing to high functional-group tolerance and the availability of nontoxic and stable arylboronic acid, palladium-catalyzed Suzuki-Miyaura cross-coupling reaction of aryl halides with arylboronic acids under the mild reaction conditions has been most extensively investigated. In this regard, the exploitation of phosphorus-based ligands has given us a distinct impression, and particularly, various sterically bulky and electron-rich tertiary phosphines ligands are recognized as efficient ligands for the Suzuki-Miyaura cross-coupling.In recent years, the discovery of stable carbenes, especially N-heterocyclic carbenes(NHCs), has enriched the chemistry of carbene. Both of organometallic chemistry and organocatalysis have greatly benefited from the chemistry of carbene. In fact, NHCs have been widely utilized as alternatives to phosphine ligands for crosscoupling reactions due to their strong electron-donating ability resembling phosphines, while having high stability toward oxygen and moisture.This article mainly use indazole and substituted indazole as skeleton to design and synthesis a series of indazole salt, and then indazole salt was used as N-heterocyclic carving precursor to apply to palladium catalytic Suzuki-Miyaura cross-coupling reaction and Heck coupling reaction.The reaction conditions of Suzuki-Miyaura cross-coupling reaction, such as palladium catalyst, solvent, temperature, alkali are optimized and found that under the optimized condition we can gain a higher yield of coupling product. On this basis, we expanded the universality of the substrate and found that the established catalysts have high universality: with boric acid, both electron-deficient substituting and rich electronic substituent aryl bromine content can carry on the coupling reaction very well.When attempted to apply the catalytic system to Heck coupling reaction, we found that the system is not work fine, instead indazole salt rearrangement reaction was happened. The rearrangement reaction’s optimum conditions was investigated. Based on this, we expanded the universality of the substrate of the rearrangement reaction and found its universality has a wide range. The mechanism of the reaction was preliminary explored by deuterium isotope markup experiment.In this paper, diversified kinds of N-replace indazole salt was synthesized, the application of palladium catalyzed Suzuki-Miyaura cross-coupling reaction was investigated, and the indazole salt rearrangement reaction was found, which enriched and developed the indazole salt as the skeleton of the research achievements of N-heterocyclic carving.