An efficient approach to H-pyrazolo[5,1-a]isoquinolines via a silver triflate-catalyzed reaction of N′-(2-alkynylbenzylidene)hydrazide with allenoate

A silver triflate-catalyzed reaction of N′-(2-alkynylbenzylidene)hydrazide with allenoate under mild conditions is described, which provides an efficient approach to diverse H-pyrazolo[5,1-a]isoquinolines. This reaction proceeds with a wide substrate scope with good functional groups tolerance.