Manganese (III) acetate mediated synthesis of polysubstituted pyrroles under solvent-free ball milling

Under solvent-free ball milling conditions, a simple and mild method was developed for efficient synthesis of 2,5-dimethyl-3,4-dicarboxylate-pyrroles and N-substituted 3,4-diphenylpyrroles via condensation-annulation of amines with acetoacetate and 2-phenylacetaldehyde, respectively. The use of cheap and safe Mn(OAc)₃ as a mediator, no use of commonly employed acetic acid as solvent, short reaction time and readily available starting materials make this protocol a good alternative to traditional synthesis of polysubstituted pyrroles.