Scheme 6.
Late‐stage modifications of halotryptophans and halotryptophan containing peptides by SMC. Reaction conditions for SMC: A) Ar‐B(OH)2 (1 equiv), Na2PdCl4 (2.5 mol %), TPPTS or TXPTS (6.25 or 25 mol %), K2CO3 (5 equiv), H2O, 40–80 °C, 4–6 h.38 B) Ph‐B(OH)2 (2.5 equiv), Pd‐ADHP (5 mol %), K2CO3 (5 equiv), H2O, 80 °C, 2–24 h.39 C) p‐Tol‐B(OH)2 (3 equiv), Pd‐ADHP (5 mol %), K2CO3 (6 equiv), H2O/EtOH 4:1, 45 °C, 48 h.40 D) Ar‐B(OH)2 (2 equiv), Na2PdCl4 (5 mol %), sSPhos (15 mol %), K3PO4 (5 equiv), H2O/dioxane 3:1, 95 °C, μwave, 30–60 min.41