Synthesis of 4,4-bis(2-hydroperoxyalkyl)pyrazolidine-3,5-diones using manganese(III)-catalyzed autoxidation

The autoxidation of a mixture of 1,2-disubstituted pyrazolidine-3,5-diones 1 and alkenes 2 in the presence of a catalytic amount of manganese(III) acetate dihydrate in air gave 4,4-bis(2-hydroperoxyalkyl)pyrazolidine-3,5-diones 3 in 75–96% yields. The structure of the bis(2-hydroperoxyethyl)pyrazolidine-3,5-dione 3 (R1=R2=Ph, R3=R4=4-FC6H4) has been corroborated by an X-ray single crystallographic analysis. On the other hand, the manganese(III) acetate oxidation of a mixture of 1 (R1=R2=Ph) and 2 (R3=R4=Ph) at elevated temperature gave 4,4-bis(2,2-diphenylethenyl)-1,2-diphenylpyrazolidine-3,5-dione (4) in good yield.