One-Step Three-Component Synthesis of Spiro Pyrrolidinones via 1,3-Dipolar Cycloaddition

Three-component 1,3-dipolar cycloaddition reactions between isatin, benzylamine, and α,β-unsaturated ketones at room temperature afforded substituted spiro[indole-3,2′-pyrrolidine] derivatives with good yields. In some cases, only one diastereoisomer was formed. The reaction involved in situ generation of azomethine ylide from isatin and benzylamine. The possibility of formation of different regio- and stereoisomers was analyzed by PM7 semiempirical quantum chemical calculations and NMR spectroscopy.