Iodine-Promoted One-pot Synthesis of Highly Substituted 4-Aminopyrroles and Bis-4-aminopyrrole from Aryl Methyl Ketones, Arylamines, and Enamines

An iodine-promoted one-pot synthesis of functionally diverse and highly substituted 4-aminopyrroles directly from aryl methyl ketones, arylamines, and enamines was developed. The reaction involves in-situ oxidation of aryl methyl ketone to glyoxal, subsequent imine formation by aniline, followed by nucleophilic addition of enamine, and cyclization to afford highly substituted 4-aminopyrroles. This reaction involved the formation of two C−N bonds and one C−C bond by a formal [1+1+3] annulation approach. The present method provides an interesting framework of two 4-aminopyrrole units directly attached to a biphenyl core by the reaction of 4,4′-diacyl biphenyl, amine, and enamine groups. This Hantzsch-type one-pot reaction provides diverse 4-aminopyrroles, which could be useful in medicinal/material chemistry.