The one-pot four-component reaction of benzohydrazide (2-picolinohydrazide), acetylenedicarboxylate, isatins and malononitrile (ethyl cyanoacetate) with triethylamine as base catalyst afforded functionalized 1-benzamidospiro[indoline-3,4'-pyridines] in good yields. (1)H NMR spectra indicated that an equilibrium of cis/trans-conformations exist in the obtained products.
Keywords: 1,4-dihydropyridine; acetylenedicarboxylate; benzohydrazide; multicomponent reaction; one-pot reaction; spiro[indoline-3,4'-pyridine].