Cu-catalyzed C-N Coupling: A Highly Efficient Synthesis Of Imidazo[1,2-α] Pyridine

Imidazopyridine compounds have a wide range of industrial applications in pharmacy, pesticide and dye industry. Imidazopyridine compounds contain fused heterocyclic structure similar indole, azaindole and purine have been aroused widespread interest, then Specific physiological activities of these compounds also appears, and put into the market for the treatment of various diseases are a very important class of drugs. Imidazopyridine compounds have anti-viral, anti-bacterial, fungicidal and anti-inflammatory characteristics and hypnotize and anxiolytic effects which can also be used to treat anxiety, insomnia, mental illness, but also as an alternate drug treatment of HIV infection, theirs potential can not be incalculable. So far, the synthesis of Imidazopyridine compounds have been extensively investigated earlier in foreign countries and a large number of paper are reported Every year, domestic researches in this area can be said to be in the ascendant that remains to be further carried out. It can be predicted that there will be more and more imidazopyridine compounds are found and applied to a wider area with the rapid development of organic chemistry, medicinal chemistry and Biochemistry.Therefore, the new synthesis method and the new derivatives of imidazopyridine compounds are still important task of the worker of synthetic organic chemistry.In view of this, we have designed and completed Imidazo[1,2-α]pyridine compounds Synthesis work. We first synthesis of N-propargylaminopyridine compounds with pyridine compounds by nucleophilic substitution reactions, the latter will be used as the basic materials for synthesising Imidazo[1,2-α]pyridine compounds, we also extends some of the N-propargylamine heterocyclic and aryl-substituted alkynyl N-propargylamine as starting materials, the reaction conditions were screened to obtain a higher yield in the expansion process. Then we further optimize reaction conditions for formation of Imidazo[1,2-α]pyridine compounds by N-propargylamine pyridines as the substrate, the application of a variety of known C-N coupling reaction of classic conditions were screened, finally the best reaction conditions were filtered out. The reaction selectively generated one of the isomers in the two known isomers to achieve the reaction purposes. In the process of the extended substrate, a portion of the substrates generated unexpected oxidation product under optimal conditions.In summary, an efficient and mild method for the synthesis of biologically imidazo [1,2-α]pyridines derivatives has been developed. In the presence of CuBr, a variety of N-propargylaminopyridines underwent the5-exo-dig heteroannulation strategy. The stereoelectronic properties of substituents on the pyridine ring and the aryl group were shown to influence the cyclization.