2-Aminopyrrole and simple 1-substituted 2-aminopyrroles: Preparation and ab initio study on the effect of solvent on the amino-imino tautomeric equilibrium

This work describes the preparation and NMR characterization of 2-aminopyrrole and simple 1-substituted-2-aminopyrroles without further substitution on the ring. The question of the effect of solvent on tautomerism in 2-aminopyrroles has been studied by using ab initio quantum mechanical methods. Theoretical calculations indicated that 2-aminopyrrole is the most stable form in chloroform and in water. Experimentally this is what was observed. Calculations indicated that in the case of the 1-methyl-2-aminopyrrole both amino and imino tautomers should be observable in water.