triethylamine in tetrahydrofuran; water 2 h; Ambient temperature;

1: 2-azidobenzoic acid With oxalyl dichloride; N,N-dimethyl-formamide in dichloromethane T=0 - 20°C; 2 h; 2: L-Pro hydrochloride With triethylamine in tetrahydrofuran; water T=0 - 20°C; 2 h; Further stages.;

1: 2-azidobenzoic acid With thionyl chloride in toluene Reflux; 2: L-proline With triethylamine T=20°C;