Synthesis of β3-Homophenylalanine-Derived Amino Acids and Peptides by Suzuki Coupling in Solution and on Solid Support

β‐Peptides and, to a certain extent, also mixed α,β‐peptides, are resistant to degradation by a variety of proteolytic enzymes that rapidly degrade natural α‐peptides. This is one of many characteristics that make β‐peptides an attractive class of compounds for drug‐discovery studies. On the other hand, modern organometallic reactions such as the Suzuki–Miyaura cross‐coupling have become standard tools in industry laboratories to derivatize side chains of α‐peptidic compounds to build up libraries of unnatural peptides. Combining both features, we prepared (4‐bromo)‐β3‐homophenylalanine derivatives 3–5 and 12 as precursors for Suzuki–Miyaura couplings. From these bromo compounds, we synthesized biaryl‐substituted β‐homoamino acids 6, and analogs 13 and 15 of the anti‐AIDS drug Saquinavir.