Reaction of 1-substituted 3,5-diamino-1,2,4-triazoles with β-keto esters: synthesis and new rearrangement of mesoionic 3-amino-2H-[1,2,4]triazolo-[4,3-a]pyrimidin-5-ones
作者:Victor M. Chernyshev、Alexander V. Astakhov、Zoya A. Starikova
DOI:10.1016/j.tet.2010.03.009
日期:2010.5
5-diamino-1-R-1,2,4-triazoles (R=Ph, Bn) with β-keto esters results in the reversible formation of N-(5-amino-1-R-1,2,4-triazol-3-yl)-substituted enaminoesters (8). Subsequent transformations depended on the reaction conditions. Compounds 8 undergo intermolecular reactions of condensation and amidation in the absence of solvent. However, in the presence of acetic acid they form 3-amino-5-oxo-2-R-2,5-dihydro-[1
3,5-二氨基-1- R -1,2,4-三唑(R = Ph,Bn)与β-酮酸酯的反应可逆地形成N-(5-氨基-1 - R -1, 2,4-三唑-3-基)-取代的氨基酯(8)。随后的转化取决于反应条件。化合物8在不存在溶剂的情况下进行缩合和酰胺化的分子间反应。然而,在乙酸的存在下,它们形成3-氨基-5-氧代-2- R -2,5-二氢-[1,2,4]三唑并[4,3 - a ]嘧啶-4-ium-8 -侧基(10),然后重排为3-氨基-1- R- [1,2,4]三唑并[4,3 - a ]嘧啶-5-酮(11)。从10到11的转变代表了偶氮嘧啶系列中的一种新型重排。乙醇中存在的乙醇胺中的烯胺酸酯8的加热,被证明是制备中离子化合物10的合适方法。