Intramolecular cyclization of Mannich reaction for synthesis of pyrimido[2,1-b]-1,3,5-tiadiazines
作者:Hassan A. H. El-Sherief、Zeinab A. Hozien、Ahmed F. M. El-Mahdy、Abdelwarth A. O. Sarhan
DOI:10.1002/jhet.471
日期:2010.11
Reaction of 6‐aryl‐5‐cyano‐2‐mercapto‐3,4‐dihydropyrimidin‐4‐ones with formaldehyde and primary amines in suitable solvent via a double Mannich reaction gave the corresponding 8‐aryl‐7‐cyano‐3‐N‐substituted‐pyrimido[2,1‐b]‐1,3,5‐thiadiazin‐6‐ones rather than the isomeric products 6‐aryl‐7‐cyano‐3‐N‐substituted‐pyrimido[2,1‐b]‐1,3,5‐thiadiazin‐8‐ones. The cyclization method was found to be the most
在适当的溶剂中,通过双曼尼希反应,使6-芳基-5-氰基-2-巯基-3,4-二氢嘧啶-4-酮与甲醛和伯胺反应,得到相应的8-芳基-7-氰基-3- N -取代-嘧啶基[2,1-b] -1,3,5-噻二嗪-6-而不是异构体产物6-芳基-7-氰基-3-N-取代嘧啶[2,1-b] -1,3,5-噻二嗪-8。发现环化方法最适合于线性产物而不是角异构体的形成。这不仅通过使用光谱分析和分子力学计算得到证实,而且通过X射线单晶结构确定得到了证实。J.杂环化学。(2010)。