2-(4'-FLUOROPHENYL)IMIDAZOLE - NITRATION STUDIES

Reactions of 2‐(4′‐fluorophenyl)imidazole (1) and related compounds under various nitrating conditions are discussed. With 90% nitric acid in 20% oleum at −10°, 1 affords 2‐(4′fluorophenyl)‐4(5)‐nitroimidazole (2) in 80% yield. Reaction of 2 with the same reagents at 25° affords 2‐(4′‐fluoro‐3′‐nitrophenyl)‐4(5)‐nitroimidazole (4) in 90% yield, whereas with 90% nitric acid in acetic acid at 95°, 2 affords 4,5‐dinitro‐2‐(4′‐fluorophenyl)imidazole (5) in 80% yield. Reaction of 1 with 70% nitric acid in concentrated sulfuric acid at 25° affords 2‐(4′‐fluorophenyl)‐5‐hyroximinoimidazolin‐4‐one (6), which rearranges and hydrolyzes to 5‐(4′‐fluorophenyl)‐1,2,4‐oxadiazole‐3‐carboxylic acid. A discussion of these reactions is presented. Copyright © 1979 Journal of Heterocyclic Chemistry