External control over tautomeric distribution and inter-conversion: new insights into the realm of catalyzed tautomerization

Abstract

This study shows that relative stabilities of two tautomeric forms for four isomeric amide–imidic acid pairs can be extensively altered by use of a simple carboxylic acid and an amine base. Further, the acid and base act as highly efficient catalysts by drastically reducing the barriers for tautomeric transformations. It is also shown that both the relative stabilities and barrier heights can be precisely modulated by changing the carboxylic acids and amine bases. The extents of both selective stabilization and barrier lowering are found to show linear dependence on the strength of the catalysts.