Oxidative halogenation of substituted pyrroles with Cu(II). PartIV.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 des- cribed 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 perfomed in the homogeneous phase with an excess of halogenating agent. The pentabromo derivative (IX), a com- pound 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