Scheme 1. Chemoenzymatic syntheses of GlcEnt–Amp/Amx 7–10. The synthetic route consists of MceC- or IroB-catalysed glucosylation of Ent-PGE3-N3 11 followed by a copper-catalysed click reaction to achieve the GlcEnt–β-lactam conjugates 7–10. We abbreviate the siderophore family 1–4 (Fig. 1a) as (Glc)Ent and the siderophore–β-lactam conjugates 5–10 as (Glc)Ent–Amp/Amx.
