Photochemical synthesis of 4(5)-nitro-2-arylimidazoles

Abstract

The irradiation at λ > 300 nm of 4(5)-nitro-2-iodoimidazole in acetonitrile in the presence of benzene gives the corresponding 2-phenyl substituted derivative. The same behaviour has been observed using m-xylene and thienyl derivatives. While the yields are nearly quantitative for benzene, m-xylene and thiophene as the aromatic partner of the imidazole derivative, the yields decrease to 50% when 2-methyl- and 2-chloro-thiophene are used as reagents. The compounds obtained by coupling of 4(5)-nitro-2-iodoimidazole and m-xylene, thiophene, 2-methylthiophene and 2-chlorothiophene have not been reported before. The observed behaviour can be explained on the basis of the previous reported data on the mechanism of the photochemical arylation of halogenothiophene.