1: N-(tert-butoxycarbonyl)-D-serine With n-butyllithium in tetrahydrofuran; hexane T=-10 - 5°C; 1 h; 2: dimethyl sulfate in tetrahydrofuran; hexane T=0 - 5°C; 9 h; 3: With sodium hydroxide; water Product distribution / selectivity; more than 3 stages;

1: With lithium hydroxide; water in tetrahydrofuran T=20°C; 4 h; 2: With hydrogenchloride in tetrahydrofuran; water T=20°C;

sodium methylate in tetrahydrofuran T=20°C; 24 h;

1: methanol With sodium hydride in tetrahydrofuran T=0 - 20°C; 0.25 h; Cooling with isopropanol-dry ice; 2: N-(tert-butoxycarbonyl)-D-serine in tetrahydrofuran T=20°C; 1 h; 3: methyl iodide in tetrahydrofuran T=20°C; 20 h;

1: methanol With sodium hydride in tetrahydrofuran T=0 - 20°C; 0.25 h; Cooling with iso-propanol/dry ice; 2: N-(tert-butoxycarbonyl)-D-serine in tetrahydrofuran T=20°C; 1 h; 3: methyl iodide With citric acid more than 3 stages;

1.1: sodium hydroxide / water / 10 h / 20 - 25 °C 2.1: sodium hydroxide / water / 0.5 h / 0 - 5 °C 2.2: 14 h / 5 - 10 °C 2.3: 0 - 5 °C View Scheme

1: N-Boc-O-methyl-D-serine With 4-methyl-morpholine; isobutyl chloroformate in tetrahydrofuran T=-78°C; Inert atmosphere; 2: benzylamine in tetrahydrofuran T=-78 - 20°C; 1 h;