One-pot electrosynthesis of 2,3-bis(spiro-2-indanyl-1,3-dione)-indeno[1,2-b]furan-4-one

The 2,3-bis(spiro-2-indanyl-1,3-dione)-indeno[1,2-b]furan-4-one has been synthesized by cathodic reduction of 2,2-dibromo-1,3-indandione in dichloromethane-Bu4NBF4. In contrast, tris-indanedione was the main product when acetonitrile was used as a solvent. Sunlight exposition of the dispiro compound afforded the tris-indandione in quantitative yield.