Pyrido[1,benzimidazole is one of the important azaheterocycles with three fused aromatic rings. These molecules containing this skeleton have wide application prospects in the fields of medicinal chemistry and materials, and their syntheses have attracted much attention in organic chemistry. According to the retrosynthetic analysis on the construction of different rings in target molecules, the research progress on the synthesis of pyrido [1,2-a]benzimidazoles from different types of starting materials is reviewed, and its future development direction is prospected.

2-Aminopyridine is a significant synthetic synthon, with unique dual nucleophilic structure. It can react with ketones, aldehydes, acids, multifunctional esters, halogenated aromatics and other compounds to synthesize five-and six-member azaheterocycles. In recent years, the cyclization reactions based on 2-aminopyridines have been under the spotlight. According to the different types of substrates, the research progress on the synthesis of imidazo[1,2-a]pyridines and pyrido[1,2-a]pyrimidines based on 2-aminopyridines in the past 5 years is reviewed, and its applications in organic synthesis methodology, drug synthesis and fluorescent probes are summarized. Furthermore, the development trend of green cyclization and its application based on 2-aminopyridines in the future are prospected. Keywords 2-aminopyridine; imidazo[1,2-a]pyridine; pyrido[1,2-a]pyrimidine; azaheterocycle; C-N bond formation; retrosynthetic analysis 吡啶环上氮原子具有较强的吸电子效应, 且吡啶 α 位基团具有特殊的作用, 使吡啶 α 位的衍生物作为合成 子或中间体在有机合成、药物合成中日益引人瞩目 [1][2][3] . 其中, 2-氨基吡啶作为最典型的一种, 因其独特的双亲 核结构特点为人们所重视 [4] , 特别是基于吡啶环上的氮 与氨基的成环反应倍受关注 [5][6][7] .