Nucleophilic Displacements of Imidazoles. I. Oxygen, Nitrogen and Carbon Nucleophiles

Abstract

4(5)- Bromo - and - iodo-imidazoles, activated by an adjacent nitro substituent, undergo nucleophilic displacement with methoxide, phenoxide , cyclic secondary chines and cyanide. The regiochemistry of the reactions of 5-iodo-4-nitroimidazole with methoxide has been confirmed by spectroscopic and X-ray methods, and a number of erroneous structures from the literature have been revised. Some apparently anomalous reactions of methoxide with 5-halo-1,2-dimethyl-4- nitroimidazoles, and of cyanide with 4-halo-1-methyl-5-nitroimidazole have been noted. The crystal and molecular structure of 5-methoxy-1-methyl-4-nitroimidazole has been determine: by direct methods. Crystals are monoclinic, P2₁/c, a 10.929(3), b 8 899(2), c 7.290(2) Å; β 92.87(2)º; Z 4. The structure was refined to R = 0.095 for 818 reflections (I > 2σI).