| Many organic reactions usually necessary the catalysis of transition metals could also be promoted by hypervalent iodine reagents,which are more desirable for the procedures of drug preparation since such transformation don’t need to consider the problem of metal residue.Quinazolone and benzimidazole,as two very important privileged structural units of biology,are widely present in a large number of bioactive natural products and drug molecules.So it is of great significance to develop more simple,efficient and transition metal-free procedure for their synthesis mediated by high valence iodine reagent.In this paper,the main progress in the hypervalent iodine reagents application in organic synthesis was reviewed.Then two research work described as the following were carried out:The first work,a new route for the synthesis of 2-alkynyl quinazolinones via C-H bond amination strategy promoted by（Diacetoxyiodo）benzene was developed.The method highlights by its short reaction time,good yields,broad substrate scope,good functional group tolerance and easily scalable up.And the presence of the highly reactive alkynyl group in the products,make them easily to be further transformed to structurally diverse of other quinazolinone derivatives.The mechanistic studies indicated that the C-H amination reaction might involve a radical process,and Hammett Competition experiments suggested that electron-donating groups can facilitate the C-N bond formation.This strategy provides a new efficient route for the synthesis of quinazolinone derivatives.The second work,the C-H bond amination reaction promoted by（Diacetoxyiodo）-benzene for the synthesis of 2-alkynyl benzimidazoles and 2-alkenyl benzimidazoles was developed.In this work we found when the alkyne ends with a hydrogen or a phenyl group,the reaction products was 2-alkynylbenzimidazole.But when the terminal group of the alkyne is replaced by methyl,the reaction gave the 2-alkenyl benzimidazole,a reduction and rearrangement products.The further transformation and application of some target products were also investigated.The advantages of the new synthesis procedure including short reaction time,broad substrate scope,good functional group tolerance,which really provide a new strategy for the synthesis of benzimidazole derivatives. |
