Nonmetal-Catalyzed Hydroamination Of Ynamides With Amines

Ynamides are nitrogen-activated alkynes,which have better regioselectivity and stereoselectivity in the reaction process due to the activation of nitrogen atom.The nitrogen atom in the ynamides structure makes the alkyne bond highly polarized due to its electron donating ability,resulting in better reactivity of ynamides than common alkynes,and the nitrogen atom is connected with an electron-withdrawing protective group,which makes the reactivity and stability of the ynamides reach a good balance.Because of the unique structures and properties of ynamides,there are used in a variety of organic chemical reactions,especially addition reactions.N-arylimines and ethene-1,1-diamines can be constructed by hydroamination of ynamides,which are key building blocks for many natural products or active compounds.For example,both N-arylimine and ethene-1,1-diamine can further synthesize the skeleton of indole compounds.Indole compounds have various biological activities such as antibacterial,anti-tumor,anti-inflammatory,and antifouling.Although many methods for the synthesis of N-arylimines and ethene-1,1-diamines by hydroamination of ynamides have been reported in recent years,most of them use expensive and environmentally unfriendly metals catalyst.Therefore,it is of great significance to explore metal-free catalyzed hydroamination of ynamides in organic synthesis.In this dissertation,50 kinds of N-arylimine compounds were prepared in 61-99%yields and 36 kinds of ethene-1,1-diamine compounds were prepared in 66-98% yields via Tf OH-catalyzed regioselective addition of ynamides with primary and secondary amines.The reaction is carried out under mild conditions,and has the characteristics of high yield,simple operation,wide functional group tolerance,and high regioselectivity.More importantly,it is the first time to realize the regioselective addition reaction of metal-free catalyzed ynamides and amines,and to synthesize a series of N-arylimine and ethene-1,1-diamine compounds in a facile,atom-economical,and efficient manner.In addition,the application of N-arylimines of addition product of ynamides and primary amines in 2-aminoindole compounds syntheses were also introduced.