Study On NBS-Participated Metal-free Cyclization-Involved Cascade Reaction

The thesis mainly focuses on the study upon the selective cyclization reaction in the presence of NBS(N-bromosuccinimide)under metal-free condition.By established methods,two series of potentially bio-active herterocycles were effectively synthesized.The manin content includes the two following parts.In the first part,the reaction between NBS and o-alkenylbenzamide compounds which the cyclization/bifunctionalization of olefins and the selective bromination of benzene rings under the condition of metal-free aqueous phase was described.Through temperature control,monobromo-and polybromo-benzoxazine compounds were efficiently synthesized.At the same time,a new synthesis of mono-and poly-bromonated isochroman compounds by the reaction of NBS with o-alkenylphenol compounds was developed.The bifunctionalization of olefinic double bonds and C-O/C-Br bond construction under ambient temperature and aqueous conditions were achieved.In the second part,the reaction of isonitrile and ?-diazoketones compound promoted by NBS was studied,the cascade reaction and alkyl migration caused by the rearrangement of a-diazoketones compound under trans-metal catalyst-free conditions and the efficient construction of polysubstituted maleimides was achieved.