2-{[2-(2-{2-[(2-{2-[(2-tert-butoxycarbonylamino-4-methyl-pentanoyl)-methyl-amino]-propionylamino}-4-methyl-octanoyl)-methyl-amino]-propionyloxy}-4-cyano-butyrylamino)-4-methyl-octanoyl]-methyl-amino}-4-methyl-pentanoic acid tert-butyl ester