A comprehensive study of the reaction scope of methyl 1,2,3-triazine-5-carboxylate (3a) with alkyl and aryl amidines is disclosed, reacting at room temperature at remarkable rates (<5 min, 0.1 M in CH₃CN) nearly 10000-fold faster than that of unsubstituted 1,2,3-triazine and providing the product pyrimidines in high yields. C4 Methyl substitution of the 1,2,3-triazine (3b) had little effect on the rate of the reaction, whereas C4/C6 dimethyl substitution (3c) slowed the room-temperature reaction (<24 h, 0.25 M) but displayed an unaltered scope, providing the product pyrimidines in similarly high yields. Measured second-order rate constants of the reaction of 3a–c, the corresponding nitriles 3e and 3f, and 1,2,3-triazine itself (3d) with benzamidine and substituted derivatives quantitated the remarkable reactivity of 3a and 3e, verified the inverse electron demand nature of the reaction (Hammett ρ = −1.50 for substituted amidines, ρ = +7.9 for 5-substituted 1,2,3-triazine), and provided a quantitative measure of the impact of 4-methyl and 4,6-dimethyl substitution on the reactivity of the methyl 1,2,3-triazine-5-carboxylate and 5-cyano-1,2,3-triazine core heterocycles.

中文翻译：

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1,2,3-三嗪-5-甲酸甲酯与脒的反应范围及C4/C6取代的影响

公开了 1,2,3-三嗪-5-羧酸甲酯 ( 3a ) 与烷基和芳基脒的反应范围的综合研究，在室温下以显着的速率反应（<5 分钟，在 CH ₃ CN 中为 0.1 M）比未取代的 1,2,3-三嗪快近 10000 倍，并以高产率提供产物嘧啶。1,2,3-三嗪 ( 3b ) 的 C4 甲基取代对反应速率几乎没有影响，而 C4/C6 二甲基取代 ( 3c ) 减缓了室温反应 (<24 h, 0.25 M) 但显示未改变的范围，以同样高的产率提供产物嘧啶。测量3a-c反应的二级速率常数，相应的腈类3e和3f以及 1,2,3-三嗪本身 ( 3d ) 与苯甲脒和取代衍生物量化了3a和3e的显着反应性，验证了反应的逆电子需求性质（Hammett ρ = -1.50 对于取代脒，ρ = +7.9（5-取代的 1,2,3-三嗪），并提供了 4-甲基和 4,6-二甲基取代对甲基 1,2,3-triazine-5- 反应性影响的定量测量羧酸盐和 5-氰基-1,2,3-三嗪核心杂环。