Synthesis of trisubstituted pyrroles via cycloamination of substituted 2-acetyl-1,4-diketones

2-Acetyl-1,4-diketones were prepared from 1-phenylbutane-1,3-dione with various substituted phenacyl bromides. These intermediates undergo cycloamination with ammonia under an additive‐ and catalyst‐free method to get trisubstituted pyrroles. An efficient, catalyst-free protocol is developed for the synthesis of substituted 3-acetyl-2,5-diarly-1H-pyrroles series (4a-m) via the Paal-Knorr cycloamination followed by the condensation method. The use of various substituted phenacyl bromides enabled the generation of a structurally diverse library of pyrrole scaffolds. Under these mild, environmentally benign conditions, a wide variety of pyrrole derivatives bearing both electron-donating and withdrawing substituents were obtained in moderate to excellent yields.