Maleic dialdehyde , from

The photooxygenation of furans was investigated initially by Schenck in the mid-forties. A crystalline and highly explosive material 32 was isolated from the parent furan by Schenck and Koch. This secondary ozonide rearranges thermally to an epoxybutanolide and a fcis-epoxide reduction with triphenylphos-phine leads to maleic dialdehyde, methanolysis to a methoxy butenolide. 

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