Microwave-Assisted Synthesis of Novel Functionalized Ketenimines and Azadienes via a Solvent-Free Reaction of Isatoic Anhydride, Alkyl-Isocyanides and Dialkyl Acetylenedicarboxylates

Ketenimines and azadienes are transient intermediates in organic chemistry especially in elimination-addition processes and in the formation of heterocyclic systems. These compounds play a considerable role as intermediates in the synthesis of heterocyclic ring systems. In this present research synthesis of novel ketenimines and azadienes via multicomponent reactions (MCRs) based on alkyl-Isocyanides is reported. Following our ongoing interest in isocyanide-based MCRs, we reported stereoselective reactions between 4H-3,1-benzoxazine-2,4(1H)-dione (isatoic anhydride) with dialkylacetylenedicarboxylates in the presence of alkyl isocyanides under solvent-free microwave conditions which leads to novel functionalized ketenimines and azadienes in a green route. The results show that the microwave-assisted leaching process has advantages over the conventional ones, concerning energy-consumption, processing time, and environmental protection.