Oxidative halogenation of substituted pyrroles with Cu(II). Part IV. Bromination of 2-(2′-hydroxybenzoyl)pyrrole. A new synthesis of bioactive analogs of monodeoxypyoluteorin

The selective bromination with copper(II) bromide of the pyrrole ring in 2-(2′-hydroxybenzoyl)pyrrole II in the heterogeneous phase is described giving in almost quantitative yield the 4,5-dibromo derivative VI. The subsequent introduction of halogen into the phenol moiety was observed when the reaction was performed in the homogeneous phase with an excess of halogenating agent. The pentabromo derivative IX , a compound very active against Staphylococcus aureus (mic = 17 nmoles per dm^?3), was obtained by exhaustive bromination of the title compound. Poor yields of chloro derivatives of II were obtained by reaction of the parent compound with copper(II) chloride.