sodium hydroxide

citrate buffer; dl-cysteine hydrochloride; papain T=50°C; 24 h;

D,L-Cysteine; citrate-buffer; papain T=40°C;

resolved on CSP cellulose tris(3,5-dimethylphenylcarbamate) by chiral HPLC;

1: 28.5 g / Cs2CO3 / dimethylformamide / 2.5 h 2: 10.69 g / CF3COOH / 96 h / Ambient temperature 3: 8.93 g / Na2CO3 / dioxane; H2O / 2.5 h / 0 °C 4: 1.) lithium bis(trimethylsilyl)amide / 1.) THF, -78 deg C, 1 h, 2.) THF, a) -78 deg C, 1 h, b) from -78 deg C to RT, 2 h 5: trifluoroacetic acid / 1.5 h / Ambient temperature 6: H2 / 10percent Pd/C / ethanol / 3 h / Ambient temperature View Scheme

methanol; palladium; acetic acid Hydrogenation;