Structures of lincosamides (A–C) and other natural compounds containing branched L-proline precursors (D–G).

(A) Lincomycin A, (B) Lincomycin B, (C) Celesticetin, (D) Anthramycin, (E) Sibiromycin, (F) Tomaymycin, (G) Hormaomycin. Fragments derived from L-proline are highlighted.