The spirobicyclic peptides 2−6 were synthesized as stereoisomeric pairs using an orthogonally protected bis(aminomethyl)malonic acid building block 1 as the branching unit. Peptide 2 was synthesized by two methods. Either the chain assembly and first cyclization were carried out on a Wang resin, and the second cyclization in solution (Scheme 1), or the whole synthesis was performed on a solid-supported