Practical synthesis of 4H-pyrido[1, 2-a]pyrimidin-4-ones using ethylene glycol as a promoting solvent

4H‐Pyrido[1,2‐a]pyrimidin‐4‐one, biologically important fused heterocyclic scaffold: Synthesis and functionalization

“…Liu and colleagues developed a green synthesis to produce bioactive scaffolds 4 H ‐pyrido[1, 2‐ a ]pyrimidin‐4‐ones 23 and 24 using ethylene glycol as green solvent (Scheme 9) [26]. 2‐Phenyl‐4 H ‐pyrido[1,2‐ a ]pyrimidin‐4‐one 24 were synthesized by ethylene glycol mediated condensation of 2‐amino pyridine 21 with alkynoate 22 whereas, to construct 2‐methyl‐4 H ‐pyrido[1,2‐ a ]pyrimidin‐4‐one 23 , 2‐amino pyridine 21 were heated with β ‐keto ester 6 in ethylene glycol.…”

Application of 2-Aminopyridines in the Synthesis of Five- and Six-Membered Azaheterocycles

“…例如, Hwang 课 题组 [78] 发现, 丙二酸二( 2 构建吡啶并[1,2-a]嘧啶化合物的常用原料 [79] . 例如, 刘 建辉课题组 [80] 发现, 乙酰乙酸乙酯和 2-氨基吡啶在乙二 醇(EG)溶剂的存在下, 经迈克尔加成、质子转移、基团 离去与分子内环化的历程, 得到 2-甲基-4H-吡啶并 [1,2-a]嘧啶-4-酮(Scheme 13).…”

“…炔酸酯还能与 2-氨基吡啶进行成环反应, 生成吡啶 并[1,2-a]嘧啶类化合物 [80] , 产物中羰基的位置通常由反 应条件和底物决定 [83] . 例如, 芳基炔酸酯与 2-氨基吡啶 在三氟甲烷磺酸银的催化下反应, 得到 4H-吡啶并 [1,2-a]嘧啶-4-酮(Eq.…”

Electrochemical Oxidative Selenation of 4H‐Pyrido‐[1,2‐a]‐pyrimidin‐4‐ones with Diorganyldiselenides

“…The condensation of triethyl orthoformate, 2,2-Dimethyl-1,3-dioxane-4,6-dione and 2-pyridinamine under heating is one of the most efficient approaches for the construction of 4H-Pyrido[1,2-a]pyrimidin-4-ones. [2] Other methods for the synthesis of substituted 4H-pyrido[1,2-a]pyrimidin-4-ones were also reported, including the °bismuth-catalyzed cyclization of ethyl acetoacetate with 2-pyridinamine, [3] ethylene glycol-promoted cyclization of 2-pyridinamine with ethyl acetoacetate [4] and some other methods. [5] In the last decades, organoselenium compounds have been gaining much attention in synthetic chemistry, owing to their useful biological activities, [6] which exhibit excellent bioactivities as enzyme inhibitors, [7] antitumor and anti-infective [8] and antioxidants, [9] and their application as fluorescence materials was also studied.…”

“…The condensation of triethyl orthoformate, 2,2‐Dimethyl‐1,3‐dioxane‐4,6‐dione and 2‐pyridinamine under heating is one of the most efficient approaches for the construction of 4H‐Pyrido[1,2‐ a ]pyrimidin‐4‐ones [2] . Other methods for the synthesis of substituted 4H‐pyrido[1,2‐ a ]pyrimidin‐4‐ones were also reported, including the °bismuth‐catalyzed cyclization of ethyl acetoacetate with 2‐pyridinamine, [3] ethylene glycol‐promoted cyclization of 2‐pyridinamine with ethyl acetoacetate [4] and some other methods [5]…”