An unexpected silver triflate-catalyzed tandem reaction of N'-(2-alkynylbenzylidene)hydrazide with ketene.

An unexpected silver triflate-catalyzed tandem reaction of N'-(2-alkynylbenzylidene)hydrazide with ketene through 6-endo-cyclization, [3+2] cycloaddition and rearrangement is reported. This reaction proceeds efficiently to generate the molecular complexity with the formation of four bonds in a one-pot procedure.