1-hydroxybenzotriazol-hydrate; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; triethylamine in N,N-dimethyl-formamide 1.) r.t., 2 days; 2.) 50 deg C, 3 h;

1: 1.a) sodium hydride; 2.) NaOH / 1.a) DMF; 2.) MeOH, H2O 2: 69 percent / 1-hydroxybenzotriazole hydrate, N-(N,N'-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, triethylamine / dimethylformamide / 1.) r.t., 2 days; 2.) 50 deg C, 3 h View Scheme

1: 1.a) sodium hydride; 2.) NaOH / 1.a) DMF; 2.) MeOH, H2O 2: 69 percent / 1-hydroxybenzotriazole hydrate, N-(N,N'-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, triethylamine / dimethylformamide / 1.) r.t., 2 days; 2.) 50 deg C, 3 h View Scheme