Study on the development of radical building block: Mn(III)-based reaction of 1,3-indanedione

The Mn(III)-based oxidation of 1,3-indanedione (1) with 1,1-diarylethenes 2a–c effectively proceeded in boiling AcOH to produce 2,2-bis(vinyl)indanediones 5a–c and 1,2'-spirobi[indene]-1',3'-diones 6a–c via the formation of 2,2-bis(2-acetoxyethyl)indanedione 3 and acetoxyindeno[1,2-b]furan-4-one 4 intermediates. On the other hand, the Mn(III)-based aerobic oxidation of 1a with 2a at room temperature resulted in bis(endoperoxide) 8a and endoperoxypropellane 9a via the production of mono(endoperoxide) 7a. The plausible reaction pathways were also discussed.