Scheme 5. Investigating the Sonogashira modification of 7-bromo tryptophan, as a component of a tripeptide with 3-fluorophenylacetylene 24. (a) Reagents and conditions: PdCl₂(CH₃CN)₂ (5 mol%), sXPhos 12 (15 mol%), Cs₂CO₃ (2.5 eq.), H₂O : CH₃CN (1 : 1), microwave heating, 100 °C, 2 h.