Formation of β-(diphenylphosphoryl)pyrroles via reactions of dibromocyclobutenylphosphine oxides with aniline

1-Phenyl-2-methyl(phenyl)-4-(diphenylphosphoryl)pyrroles are obtained, unexpectedly instead of the 1-phenyl-4-methyl(phenyl)-2-(diphenylphosphoryl)pyrrole regioisomers from a series of reactions between 1,4-dibromo-2-methyl(phenyl)-4-diphenylphosphorylcyclobutenes and aniline via nucleophilic substitution accompanied by an allylic shift, subsequent retro electrocyclization and pyrrole ring closure.