Scheme 6. Naturally occurring halopyrrole containing compounds. (A) The biogenesis of pyrrolnitrin 24 involving a variant A FDH PrnC. (B) The enzyme tethered biosynthesis of halopyroles from proline, employing variant B FDHs. (C) Bioactive compounds containing halopyrroles including pyrrolnitrin 24,³⁴ pentachloropseudilin 71,¹⁵¹ chlorizidine A 131,¹⁶² hormaomycin 132,¹⁶³ pyoluteorin 133,¹⁶⁴ pyrrolomycins 134–137¹⁶⁵ and marinopyrrole 138,¹⁶⁶ noting the halogenases utilised in their construction. (D) Biocatalytically vanadium-dependent bromoperoxidases may be utilised to monobrominate thiophene and pyrroles.¹⁶⁷ Chlorination is colour coded blue.