N-Iodosuccinimide-Promoted Selective Construction of Cyclopropyl and Dihydrofuranyl Spirooxindoles from Alkylidene Oxindoles and Annular β-Dicarbonyl Compounds

Abstract

An efficient N-iodosuccinimide-promoted cyclization of readily available alkylidene oxindoles with annular β-dicarbonyl compounds has been demonstrated. With five-membered cyclic β-dicarbonyl compounds as the starting materials, a series of cyclopropyl oxindoles can be obtained in good to excellent yields, whereas it almost quantitatively affords dihydrofuranyl spirooxindoles when six- or seven-membered cyclic β-dicarbonyl compounds are employed. This protocol provides a new alternative to the practical synthesis of structurally diverse spirooxindoles.

Aerobic CuBr2-Catalyzed Oxidative Coupling Reaction of Amidines with Exocyclic α,β-Unsaturated Cycloketones for the Synthesis of Spiroimidazolines

“…Inspired by the great importance of spiroimidazoline derivatives, the remarkable versatility of aerobic copper catalysis, accompanied by our continued interest in the synthesis of spirocyclic compounds, , we investigated the aerobic copper-catalyzed oxidative coupling reaction of amidines with exocyclic α,β-unsaturated cycloketones and developed a new method for the synthesis of spiroimidazolines. Compared with similar methods, , this protocol does not need to employ expensive devices and stoichiometric promoters, and only a catalytic amount of inexpensive CuBr 2 was used.…”

NIS-Promoted Chemodivergent and Diastereoselective Synthesis of Pyrrolinyl and Cyclopentenyl Spiropyrazolones via Regulated Cyclization of Alkylidene Pyrazolones with Enamino Esters

“…In light of these points and inspired by our recent work on halogen-promoted tandem reaction for synthesizing spirocyclic compounds, we thus attempted to construct structurally novel spiropyrazolones from the reaction of alkylidene pyrazolones with enamino esters through Michael addition, halogenation, and intramolecular nucleophilic substitution processes (Scheme ). We envisaged that the N-attacking or C-attacking cyclization pathway in the intramolecular nucleophilic substitution of the in situ-generated halides may be regulated by employing suitable reaction conditions.…”