1: N-[(phenylmethoxy)carbonyl]-L-tyrosine phenylmethyl carbonate With benzotriazol-1-ol; dicyclohexyl-carbodiimide in ethyl acetate T=0°C; 0.166667 h; 2: ethyl 2-(4-piperidyloxy)-acetate in DMF (N,N-dimethyl-formamide); ethyl acetate T=0°C; 18 h;