1: N-(1-(S)-Ethoxycarbonylbutyl)-L-alanine With 1,1'-carbonyldiimidazole in acetonitrile T=10°C; 3 h; 2: (2α,3aβ,7aβ)-octahydro-1H-indole-2-carboxylic acid in acetonitrile T=10°C; 5 h;

1: (2α,3aβ,7aβ)-octahydro-1H-indole-2-carboxylic acid With chloro-trimethyl-silane; 1,1,1,3,3,3-hexamethyl-disilazane in acetonitrile T=25 - 30°C; 3 - 3.5 h; Heating / reflux; 2: With triethylamine in dichloromethane; acetonitrile T=0 - 5°C; 0.0833333 - 0.166667 h; 3: N-[1(S)-ethoxycarbonylbutyl]-(S)-alanine-2'-benzothiazolylthio ester in dichloromethane; acetonitrile T=-20 - 30°C; 16 - 17 h; Product distribution / selectivity;

triethylamine in dichloromethane; acetonitrile T=60°C; 4 h; Heating / reflux; Product distribution / selectivity;

1: (2α,3aβ,7aβ)-octahydro-1H-indole-2-carboxylic acid With chloro-trimethyl-silane; triethylamine in dichloromethane T=20 - 25°C; 3 h; 2: (S)-N-[(S)-1-(ethoxycarbonyl)butyl]alanine With 1H-imidazole; thionyl chloride in dichloromethane T=-10 - 25°C; 23 h; 3: With sodium hydroxide in dichloromethane; water pH=5 - 6; Product distribution / selectivity;

1: (2α,3aβ,7aβ)-octahydro-1H-indole-2-carboxylic acid With chloro-trimethyl-silane; triethylamine in dichloromethane T=20 - 25°C; 2 h; 2: N-[1(S)-ethoxycarbonyl-1-butyl]-(S)-alanyl chloride hydrochloride in dichloromethane T=-15 - 0°C; 2 h; 3: With sodium hydroxide in dichloromethane; water pH=4.2; Product distribution / selectivity;

1.1: triphenylphosphine / CH2Cl2 / 0.75 h 1.2: 46 percent / CH2Cl2 / 2.5 h / 25 - 30 °C 2.1: triethylamine / CH2Cl2 / 4 h / -15 - -10 °C 3.1: hydrogen / Pd/C View Scheme

1: triethylamine / CH2Cl2 / 4 h / -15 - -10 °C 2: hydrogen / Pd/C View Scheme

1: triethylamine / CH2Cl2 / 4 h / -15 - -10 °C 2: hydrogen / Pd/C View Scheme

tert-butylamine in ethyl acetate; acetonitrile Heating / reflux;

in ethyl acetate Heating / reflux;