Multicomponent Cascade Reaction of 3-Cyanochromones: Highly Site-Selective Synthesis of 2-(1H-Imidazol-1-yl)-4H-chromen-4-one Derivatives

A method for the synthesis of 2-(1H-imidazol-1-yl)-4H-chromen-4-one derivatives (IMCMs) from 3-cyanochromones and α-isocyanoacetates via a one-pot cascade reaction involving a 1,2-addition, Michael reaction, ring-closing, tautomerization, ring-opening, and [3 + 2] cyclization was enabled by refluxing a mixture of the starting materials in THF in the presence of Ag2CO3as a catalyst. The cascade reaction resulted in the formation of five bonds and the cleavage of two bonds, including a triple bond, in one pot. This protocol enabled not only the synthesis of functionalized imidazoles (i.e., IMCMs) but also the synthesis of functionally useful enamine building blocks. This strategy is suitable for combinatorial and parallel syntheses of IMCMs.