Three-component reaction of N′-(2-alkynylbenzylidene)hydrazide, α,β-unsaturated carbonyl compound, with bromine

Different outcomes were generated under different conditions for the three-component reaction of N′-(2-alkynylbenzylidene)hydrazide, α,β-unsaturated carbonyl compound, with bromine. 6-BromoH-pyrazolo[5,1-a]isoquinoline was obtained when the reaction was performed in NMP at 70 °C in the presence of DABCO as base, while 6-bromo-1,2,3,10b-tetrahydropyrazolo[5,1-a]isoquinoline was afforded when the reaction occurred in DMAc at 10 °C in the presence of K3PO4 as the base.