in dichloromethane T=0 - 20°C; 18.1667 h;

1: (R)-1-(t-butoxycarbonyl)-3-pyrrolidinocarboxylic acid With chloroformic acid ethyl ester; triethylamine in tetrahydrofuran T=0 - 5°C; 2: ethanol With 4-(N,N-dimethlyamino)pyridine in tetrahydrofuran T=20°C; 1 h;

triethylamine; dimethylaminopyridine in tetrahydrofuran; ethanol T=0 - 20°C; 1.5 h;

sodium tetrahydroborate in tetrahydrofuran; methanol T=0°C; 42.5 h;