Metabolic and photochemical hydroxylation of 5-nitro-2-furancarboxaldehyde derivatives

The potassium salt of 1-[[(5-aco-nitro-4,5-dihydro-4-oxo-2-furanyl)methylene]amino]-2,4-imidazolidinedione (4) was isolated from the urine of rats fed nitrofurantoin. An aldehyde absorbing at 400 nm was synthesized photochemically, in less than 1% yield, from 5-nitro-2-furancarboxaldehyde diacetate (1), and the hydroxylamine (2), 3-amino-2-oxazolidinone (3a-c), and 1-amino-2,4-imidazolidinedione (4) derivatives were prepared. On the basis of ir and NMR data 2, 3b,c, and 4 are considered derivatives of 4-hydroxy-5-nitro-2-furancarboxaldehyde which are mainly in the aci-nitro form. Methyl and ethyl nitronic esters of 3b were synthesized. The photochemical hydroxylation of 1 also yields 3,4-dihydroxy-5-nitro-2-furancarboxaldehyde, isolated as 3-[[(3,4-dimethoxy-5-nitro-2-furanyl)-methylene[amino[-2-oxazolidinone (7).