(tert-Butoxycarbonyl)glycyl-glycyl-glycyl-glycyl-glycine is a peptide featuring five glycine residues. Its C-terminus is free for reactions such as in coupling to form amides, while its N-terminus is Boc-protected. The Boc can be removed with acid to allow the amine to participate in a wide variety of reactions such as couplings, reductive aminations, SNAr and so on.