The coupling of a terminal alkyne and an aromatic ring is the pivotal reaction when talking about applications of the copper-promoted or copper-free Sonogashira reaction. The list of cases where the typical Sonogashira reaction using aryl halides has been employed is large, and choosing illustrative examples is difficult. A recent use of this methodology is shown below for the coupling of iodinated phenylalanine with a terminal alkyne derived from d-biotin using an in situ generated Pd species as catalyst, which allowed the preparation of alkyne-linked phenylalanine derivative for bioanalytical applications. There are also examples of the coupling partners both being attached to allyl resins, with the Pd catalyst effecting cleavage of the substrates and subsequent Sonogashira
coupling in solution.