Synthesis for polycyclic spirooxindoles via base promoted spiroannulation reaction of cyclic β-enaminones and MBH maleimides of isatins

Abstract

An efficient synthetic protocol for polycyclic spirooxindoles was developed by base promoted spiroannulation reaction of cyclic β-enaminones and MBH maleimides of isatins in acetonitrile at elevated temperature. This reaction not only afforded functionalized spiro[indoline-3,9′-pyrrolo[3,4-b]quinoline]-1′,2,3′,8′-tetraones in satisfactory yields via spiroannulation reaction, but also gave unexpected dihydrospiro[indoline-3,9′-pyrrolo[3,4-b]quinoline]-1′,2,3′,8′-tetraone derivatives via further rearrangement process. The chemical structures of the two kinds of the spirooxindoles were confirmed by X-ray diffraction single crystal determination.