The reaction between amines and carboxylic aicds in the presence of polyphosphoric acid trimethylsilyl ester (PPSE) has been investigated from the view point of the synthesis of amides and amidines. Benzanilide was selectively prepared from benzoic acid and aniline in the presence of PPSE and pyridine at 100 °C, whereas a mixture of benzanilide and N,N′-diphenylbenzamidine was obtained without the
从合成酰胺和脒的角度研究了胺和羧酸在多磷酸三甲基甲硅烷基酯(PPSE)存在下的反应。在 PPSE 和吡啶的存在下,在 100°C 下,苯甲酸和苯胺有选择地制备苯甲酰苯胺,而在不使用吡啶的情况下获得苯甲酰苯胺和 N,N'-二苯基苯甲脒的混合物。在 160 °C 下的反应几乎完全得到 N,N'-二苯基苯甲脒。通过简单地在 160 °C 下与四摩尔量的 PPSE 加热,可以从羧酸和芳香胺的组合中以高产率获得各种对称脒。在相同条件下,脂肪族和芳香族胺与 N-单取代和 N,N-二取代酰胺的反应也得到相应的不对称脒。
A NOVEL DIRECT SYNTHESIS OF AMIDINES FROM CARBOXYLIC ACIDS AND AMINES USING POLYPHOSPHORIC ACID TRIMETHYLSILYL ESTER (PPSE) AS CONDENSING AGENT
It was found that amidines were obtained directly by the reaction of carboxylic acids with amines in the presence of PPSE, and the yields of amidines were dependent on the structure of amines rather than that of carboxylic acids.