Scheme 1.

Synthesis of LecA inhibitors targeting the central pocket. The different side chains were introduced in the penultimate step via amide coupling with alkyne S9. Final assembly was achieved by coupling azide S6 with alkynes S10a–i in a copper(I)‐catalyzed cycloaddition. Reagents and conditions: (i) BF₃⋅OEt₂, S2, CH₂Cl₂, 0–25 °C, 18 h; (ii) 1. LiI, pyridine, 25 °C, 3 d; 2. S4, HOBt, EDC, DMF, 25 °C, 24 h; (iii) NaOMe, MeOH, 25 °C, 1.5 h; (iv) SOCl₂, MeOH, 0–25 °C, 18 h; (v) ethanolamine, 25 °C, 18 h; (vi) various acetic acids, EDC, HOBt, DIPEA, DMF, 25 °C, 18 h; (vii) S6, CuSO₄ in H₂O, sodium ascorbate in H₂O, DMF, 25 °C, 2 h.