Abstract The photochemical behaviour of 2-methyl-5-nitro-1H-imidazoles 1 in water- containing solutions has been studied. In a first reaction step, the photorearrangement of 1 yields 2-methyl-2-imidazoline-4, 5-dione-4-oximes 2. Hydrolysis of 2 and subsequent elimination of water from a supposed intermediate 5 leads to 5-methyl-1, 2, 4-oxadiazole-3- carboxamides 4. The basic structure of 4 was determined by X-ray analysis of the ...
