Reaction of 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione (3) with two equivalents of cyclic 1,3‐dicarbonyl compounds under acid catalysis generates spiro[4H‐pyran‐3,3′‐oxindoles] 7. In contrast, though base catalysis also achieves double addition, the final products 8 result from subsequent ring opening of the five‐membered lactam via intramolecular attack by enolate; these products can be converted into the spiro[4H‐pyran‐3,3′‐oxindoles] by treatment with acid.