1: Boc-Val-NMe(OMe) With diisobutylaluminium hydride in dichloromethane T=-78°C; 0.666667 h; 2: Bestman-Ohira reagent With potassium carbonate in dichloromethane T=20°C; 8 h; Further stages.;

potassium carbonate in methanol T=0 - 20°C; 16 h;

n-butyllithium in tetrahydrofuran T=-78°C; 1 h;

sodium hydride in tetrahydrofuran 0.25 h;

1: tert-butyl 1-(methoxy(methyl)amino)-3-methyl-1-oxobutan-2-ylcarbamate With lithium aluminium tetrahydride in tetrahydrofuran T=20°C; 0.5 h; Inert atmosphere; 2: (1-Diazo-2-oxo-propyl)-phosphonic acid dimethyl ester in methanol T=0°C; 0.5 h; Inert atmosphere; 3: With potassium carbonate in methanol T=20°C; 15 h; Inert atmosphere;

potassium carbonate in dichloromethane T=20°C; pH=11; 17 h;

1: 72 percent / CH2Cl2 / 16 h / Ambient temperature 2: 83 percent / BuLi / tetrahydrofuran / 1 h / -78 °C View Scheme

1.1: triethylamine / dichloromethane / 20 °C 2.1: 2,6-bis[(4S)-4-methyl-4,5-dihydrooxazol-2-yl]pyridine; copper(l) iodide / methanol / 18 - 25 °C 2.2: 24 h / 18 - 25 °C 3.1: [bis(acetoxy)iodo]benzene / methanol; acetonitrile / 2.5 h / 20 °C 3.2: 1.5 h 4.1: potassium carbonate / dichloromethane / 17 h / 20 °C / pH 11 View Scheme

1.1: 2,6-bis[(4S)-4-methyl-4,5-dihydrooxazol-2-yl]pyridine; copper(l) iodide / methanol / 18 - 25 °C 1.2: 24 h / 18 - 25 °C 2.1: [bis(acetoxy)iodo]benzene / methanol; acetonitrile / 2.5 h / 20 °C 2.2: 1.5 h 3.1: potassium carbonate / dichloromethane / 17 h / 20 °C / pH 11 View Scheme