Synthesis and N-alkylation of 2-alkyl- and 2-arylimidazole-4,5-dicarboxylic acid esters

Nitration of D-tartaric acid, followed by treatment of the resulting dinitrotartaric acid with ammonia and aldehydes gave 2-phenyl-, 2-(2-pyridyl)-, 2-isopropyl-, and 2-isobutylimidazole-4,5-dicarboxylic acids. Some factors affecting the yield of the final products were revealed, and optimal conditions for their esterification were found. N-Alkylation of 2-substituted imidazole-4,5-dicarboxylates thus obtained involves considerable steric hindrances; therefore, the corresponding N-alkyl derivatives can be obtained in a poor yield only in the presence of such a strong base as 1,8-diazabicyclo[5.4.0]undec-7-ene.