1: 71 percent / 1-<3-(dimethylamino)propyl>-3-ethylcarbodiimide, K2CO3 / dimethylformamide / 20 h / 24 °C 2: 91 percent / NaH / tetrahydrofuran; dimethylformamide / 0.42 h / 24 °C View Scheme

potassium carbonate; N'-(3-dimethylaminopropyl)-N-ethylcarbodiimide in N,N-dimethyl-formamide T=24°C; 20 h;

Multi-step reaction with 4 steps 1: 97 percent / bis(2-oxo-3-oxazolidinyl)phosphinic chloride, Et3N / CH2Cl2 / 9 h / 21 °C2: 100 percent / trifluoroacetic acid / 1 h / 23 °C3: 81 percent / CH2Cl2 / 22 h / 23 °C4: 98 percent / aq. LiOH / tetrahydrofuran; methanol / 10 h / 50 - 55 °C  

With  sodium hydrogencarbonate; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride in  N,N-dimethyl-formamide T=24°C; 17 h;