Enantioselective 1,3-Dipolar Cycloaddition of Methylene­indolinones with α‑Diazomethyl­phosphonate to Access Chiral Spiro-phosphonyl­pyrazoline-oxindoles Catalyzed by Tertiary Amine Thiourea and 1,5-Diaza­bicyclo­[4.3.0]­non-5-ene

A methodology to access chiral 3,3′-spiro-phosphonyl­pyrazoline oxindoles via an asymmetric 1,3-dipolar cycloaddition reaction of substituted methylene­indolinones with α-diazomethyl­phosphonate in the catalysis of tertiary amine thiourea and 1,5-diaza­bicyclo­[4.3.0]­non-5-ene (DBN) has been established. This method exhibits high functional group compatibility, where a wide range of methylene­indolinones with various substituents and heterocyclic rings are accommodated by this reaction. The resulting chiral 3,3′-spiro-phosphonyl­pyrazoline oxindoles can be further transformed into spiro-phosphonyl­cyclo­propane oxindoles by ring contraction.