L-Proline, (4R)-1-acetyl-4-azido-L-prolyl-(4R)-4-azido-L-prolyl-(4R)-4-azido-L-prolyl -(4R)-4-azido-L-prolyl-(4R)-4-azido-L-prolyl-(4R)-4-azido-L-prolyl-(4R)-4- azido-L-prolyl-(4R)-4-azido-L-prolyl