Convenient Synthesis of Methyl 1-Methyl-2,4-dibromo-5-imidazolecarboxylate

Article abstract of DOI:10.1055/s-1988-27702

Three syntheses of methyl 1-methyl-2,4-dibromo-5-imidazolecarboxylate (8) are presented.One proceeds from sarcosine via ring closure, bromination, and desulfurization.The second uses N-methylimidazole, polybromination, and selective halogen-metal interchange.The third and most efficient and preparatively useful route begins with diaminomaleonitrile (13).Ring closure with triethyl orthoformate followed by methylation and hydrolysis affords 1-methyl-4,5-imidazoledicarboxylic acid (16).Regioselective decarboxylation followed by esterification yields methyl 1-methyl-5-imidazolecarboxylate (18).Subsequent dibromination gives the completely substituted imidazole 8.The primary purification in this sequence is fractional sublimation of 18 after the esterification step.An overall yield of 26percent is achieved from diaminomaleonitrile (13) to methyl 1-methyl-2,4-dibromo-5-imidazolecarboxylate (8), which is a key intermediate for the synthesis of tricyclic imidazo cooked food mutagens.