The Cs2CO3-Catalyzed Reaction of 2-Oxindoles with Enones for the Preparation of Indolin-3-Ones and Their Further Transformation.

The Cs2CO3-catalyzed reaction of 2-oxindoles with enones affords 2,2-disubstituted indolin-3-ones through domino "Michael addition-oxidation-ring-cleavage-C-N coupling" process. O2 acts as the sole oxidant to accomplish the oxidative process. The indolin-3-ones can be further transformed to pyridazine, azirdine-fused 3-oxindoles, 4-quinolone derivatives easily.