Difunctional Amino-oriented Selective Bromination of Pyridine
Using 2-amino-3-bromopyridine as the template substrate,eosin Y,rhodamine B,rose bengal,methylene blue,and 10-methyl-9-trimethylphenylacridine perchlorate([Acr-Mes]+(ClO4)-)five kinds of photocatalysts and N-bromophthalimide(NBP),N-bromosuccinimide(NBS),N-bromosaccharin(NBSA),dibromohydantoin(DBDMH)four bromine sources,the results showed that by introducing an amino bifunctional directing group and using the site-occupying principle,the selective bromination reaction of pyridine was achieved without the need for an external catalyst.Using NBS as the bromine source and acetonitrile as the solvent,the yield could reach up to 92%.And the reaction was extended to heterocyclic structures such as quinoline,pyrazole,and indole.The reaction did not require the addition of any catalyst additives and could occur at room temperature.The conditions were simple,the substrate range was wide,the raw materials were easily available,the reaction system was simple,the reaction time was short,and it was green and environmentally friendly.It provided a new method for the halogenation of pyridine and other aromatic heterocycles method.
difunctional amino orientationpyridineelectrophilic brominationgreen and environmentally friendlyselective bromination
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维普
