After the coupling, he deprotects his resin-bound peptide with 20% piperidine in DMF, and then completes the synthesis in the usual way by coupling Fmoc-Gly, deprotecting the peptide, and removing it from the resin. He is shocked to find a mixture of several peptide products. Two of them contain one residue of each of the amino acids Ala, Gly, and Lys, and one contains two residues of Gly, one residue of Ala, and one residue of Lys. Suggest a structure for each product and explain how each is formed.