- A potassium amide induced ring transformation of 1,2,4-triazines into 1,2,4-triazoles and 1,3,5-triazines
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5-Phenyl- and 3,5-diphenyl-1,2,4-triazine, when treated with potassium amide in liquid ammonia, are converted into a mixture of phenyl derivatives of 1,2,4-triazole and amino-1,3,5-triazines. The ring contraction of the 1,2,4-triazine ring into the 1,2,4-triazole ring has been explained by an initial addition of the amide ion to C-6, ring opening by fission of the N1-C6 bond and ring closure (ANRORC-mechanism). The transformation of the 1,2,4-triazine ring into the 1,3,5-triazine ring has been studied by means of 15N-labeled potassium amide. It was found that the nitrogen of the amide ion becomes one of the ring nitrogen atoms in the 1,3,5-triazine ring and that the exocyclic amino group is imlabeled. Based on these 15N-labeling studies, it is proposed that this ring transformation starts with an initial addition of the amide ion to C-5, ring opening between C-5 and C-6, a dehydrogenative rearrangement of the open-chain intermediate 1-amino-2,4,5-triazahexatriene into 1-amino-4-cyano-2,4-diaza-1,3-butadiene, and ring closure.
- Rykowski,Van Der Plas
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- Base-mediated synthesis of unsymmetrical 1,3,5-triazin-2-amines via three-component reaction of imidates, guanidines, and amides or aldehydes
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A simple and efficient method for the basemediated synthesis of unsymmetrical 1,3,5-triazin-2-amines has been developed. The protocol uses readily available imidates, guanidines, and amides or aldehydes as the starting materials, cesium carbonate as the base, no catalyst or additive is required, and the three-component reaction provides diverse 1,3,5-triazin-2-amines in moderate to good yields with tolerance of wide functional groups.
- Pan, Liyang,Li, Zhenxing,Ding, Tao,Fang, Xiaomin,Zhang, Wenkai,Xu, Hao,Xu, Yuanqing
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p. 10043 - 10050
(2018/05/31)
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