1: N-tert-butoxycarbonyl-D-phenylalanine With triethylamine in dichloromethane Inert atmosphere; 2: With (benzotriazo-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate Inert atmosphere; 3: O,N-dimethyl-hydroxylamine hydrochloride With triethylamine Inert atmosphere;

4-methyl-morpholine in methanol; dichloromethane; water; isobutyl chloroformate

benzotriazol-1-ol; N'-(3-dimethylaminopropyl)-N-ethylcarbodiimide

lithium aluminium tetrahydride in tetrahydrofuran T=0°C; Reduction; 1 h;