The 1,3-diyne linker as a rigid 'i,i+7' staple for α-helix stabilization : stereochemistry at work

Short alphahelical peptide sequences were stabilized through Glaser-Hay couplings of propargylated l- and/or d-serine residues at positions i and i+7. NMR analysis confirmed a full stabilization of the helical structure when a d-Ser (i), l-Ser (i+7) combination was applied. In case two l-Ser residues were involved in the cyclization, the helical conformation is disrupted outside the peptide's macrocycle