An efficient synthesis of newN-alkyl- andN-aryl-3-oxido-1H-imidazole-4-carboxamides based on exploration of inexpensive, commercially available ethyl acetoacetate, paraformaldehyde and primary amines is described. Representative compounds were tested in selected transformations, such as ‘sulfur-transfer reaction’ leading to imidazole-2-thiones and isomerization to corresponding imidazol-2-ones. Strong intramolecular hydrogen bonding via theN-oxide function results in the reduced reactivity of 3-oxido-1H-imidazole-4-carboxamides in both reactions. Moreover, the palladium catalyzed C(2)-arylation of imidazole ring as well as azide-alkyne [3+2] cycloaddition using theN-propargyl substituted 4-carboxamide derived from an imidazole 3-oxide as a dipolarophile, were also studied.
基于对廉价、商业可获得的乙酰乙酸乙酯、多聚甲醛和一级胺的探索,描述了一种高效合成新的N-烷基和N-芳基-3-氧代-1H-咪唑-4-羧酰胺。代表性化合物在选择性转化中进行了测试,例如引导到咪唑-2-硫醚的“硫转移反应”和异构化为相应的咪唑-2-酮。通过N-氧化物功能强的分子内氢键作用导致3-氧代-1H-咪唑-4-羧酰胺在两种反应中的反应性降低。此外,还研究了钯催化的咪唑环上的C(2)-芳基化反应,以及使用从咪唑-3-氧代衍生的N-丙炔基取代的4-羧酰胺作为双极亲核试剂的偶氮炔[3+2]环加成反应。