Spiro[4H-2,3-dihydropyran-3,3-oxindoles] derived from 1,2,3,4-tetrahydroquinoline

Knoevenagel condensation of 5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinoline-1,2-dione 3 with aryl cyanomethyl ketones 9 generates 3-(aroyl(cyano)methylidene)oxindoles 10 that react with cyclic 1,3-diketones 11 to generate polycyclic hemiacetal spiro[4H-2,3-dihydropyran-3,3-oxindoles] 13.