1: (S)-2-phenylglycine With N,N-dicyclohexylamine in acetone T=20°C; 2: 1-[[(9H-fluoren-9-ylmethoxy)carbonyl]oxy]-2,5-pyrrolidinedione With sodium carbonate in water; acetonitrile T=0 - 20°C; pH=8; 3: With potassium hydrogensulfate in water; acetonitrile pH=2 - 3;

hydrogenchloride; n-Pentyl nitrite; N-ethyl-N,N-diisopropylamine 1.) dioxane, DMF, 1 h, -15 deg C, 2.) DMF, 4 h, -15 deg C to room temp., 36 h, room temp.; Yield given. Multistep reaction. Yields of byproduct given;

1: With 4-methyl-morpholine; chloroformic acid ethyl ester in tetrahydrofuran T=-10°C; 0.166667 h; 2: With sodium tetrahydroborate in tetrahydrofuran 3: With water in tetrahydrofuran

1.1: Fmoc-Cl; N-methylmorpholine / tetrahydrofuran / 0.17 h / -15 °C 1.2: 86 percent / tetrahydrofuran; diethyl ether / 0 - 20 °C 2.1: 82 percent / silver benzoate / dioxane; H2O / 0.02 h / microwave irradiation View Scheme