Abstract
Tetrahydrospiro[chromene-4,3'-indole]-2-ones (5a-c) and spiro[indole-3,4'-pyrano(3',2'-d)pyrazole]-2-ones (6a-b) have been synthesized based on the one-pot three-component cyclocondensation reaction of 5-(un)substituted isatins (1a-c) with ethyl cyanoacetate (2) and 5,5-dimethylcyclohexane-1,3-dione (3) or 5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one (4) in absolute ethanol containing a catalytic amount of Et3N carried out under both conventional heating and environmentally benign procedures. The structures of the resulting compounds were confirmed by spectral {IR, H-1 NMR, C-13 NMR, 2D NMR [H-1-H-1 COSY, H-1-C-13 COSY (HETCOR)] and electrospray ionization tandem mass [(+/-) ESI-MS/MS]} analysis.