Tandem reactions of N'-(2-alkynylbenzylidene)hydrazides with silyl enolates: a facile route to H-pyrazolo[5,1-a]isoquinolines.

A silver triflate-catalyzed tandem reaction of N'-(2-alkynylbenzylidene)hydrazide with silyl enolate is described, which generates the unexpected H-pyrazolo[5,1-a]isoquinolines in good to excellent yields. Intramolecular cyclization, nucleophilic addition, condensation, and aromatization may be involved in the reaction process.