Synthesis And Reactions Of Ynamides And Allenamides

Ynamides and allenamides, special classes of functionalized alkynes and allenes,are powerful and versatile synthetic building blocks and important synthons in modern organic synthesis. According to the structure characteristics of ynamides and allenamides, the research work of this thesis has been focused on exploring the nucleophilic addition reaction of ynamides and aldehydes, the hydroamination reaction of ynamides and diphenylsulfonimide and the cyclization reaction of allenamides and amines.Firstly, based on the special structure of N,N-disulfonyl ynamides, we designed a tandem reaction: N,N-disulfonyl ynamides and a nucleophile PrOLi generated ketenimine intermediate in-situ, then the intermediate reacted with aldehydes to obtain the α,β- unsaturated amides. For substituted salicylaldehyde, in the presence of a mild base triethylamine, N,N-disulfonyl ynamides reacted with salicylaldehyde to afford iminocoumarins derivatives.Secondly, in the continuation of our investigation of hydroamination reaction of ynamides, we proposed the hydroamination reaction of ynamides and diphenylsulfonimide. Without any catalyst, various ynamides and diphenylsulfonimide react under mild conditions to afford 1,1-diamine ethene which are difficult to prepare by other methods. In addition, the product could easily undergo desulfonylation reaction to afford the important compounds N-sulfonyl amidine derivatives.Thirdly, in the process of investigation on the addition reaction of electron-withdrawing group substituted allenamides and amines, we found an unexpected product imidazoles which are important heterocyclic compounds. Then we carried out a detailed research about the reaction, and established a novel regioselective synthesis of highly substituted imidazoles from electron-withdrawing group substituted allenamides with amines. The imidazol-4- or imidazol-5-ylphosphonates, phosphine oxides and carboxylates were constructed regioselectively depending on the substitutes on the nitrogen atoms.These three types of novel reactions extended the content of ynamides and allenamides and provided efficient methods for the synthesis of a variety of important nitrogen-containing small molecules and heterocyclic compounds.