Amidines. II. Preparation of unsymmetrical N1,N2-disubstituted amidines.
作者:Machiko ONO、Reiko TODORIKI、Shinzo TAMURA
DOI:10.1248/cpb.38.866
日期:——
Unsymmetrical N1, N2-disubstituted amidines were prepared by conventional and newly developed methods. Reaction of N1-tosyl-N1, N2-diarylacetamidines and arylamines gave unsymmetrical acetamidines in the presence of basic catalysts, and N1-acyl-N1, N2-di(p-nitrophenyl)formamidines and arylamines gave unsymmetrical formamidines under neutral conditions. Unsymmetrical amidines exist as tautomeric mixtures in solution owing to proton transfer between the two nitrogen atoms, and it was proved on the basis of proton nuclear magnetic resonance (1H-NMR) evidence that the tautomer in which the hydrogen is attached to the more basic nitrogen atom is predominant.
不对称的N1、N2-二取代氨基脲通过传统方法和新开发的方法制备而成。N1-对苯磺酰基-N1、N2-二芳基乙酰氨基脲与芳胺反应,在碱性催化剂的存在下生成不对称乙酰氨基脲,而N1-酰基-N1、N2-二(对硝基苯基)甲酰氨基脲与芳胺在中性条件下生成不对称甲酰氨基脲。不对称氨基脲因两个氮原子之间的质子转移而在溶液中以 tautomeric 混合物的形式存在,并且基于质子核磁共振 (1H-NMR) 的证据证明,氢原子与更基本的氮原子结合的 tautomer 是占主导地位的。