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.
Acid hydrolysis of unsymmetrical N1, N2-disubstituted acetamidine and formamidine was examined kinetically in aqueous dioxane solution. The reaction afforded the more basic amine and the N-acyl derivative of the less basic amine. Increasing the dioxane content in the solvent increased the reaction rate. The reaction can be rationalized in terms of specific acid-general base catalysis.