dicyclohexyl-carbodiimide in N,N-dimethyl-formamide 24 h;

1: aq. Na2CO3 / dioxane / 3 h 2: aq. NaOH / methanol / 6 h / 60 °C 3: 85 percent / DCC / dimethylformamide / 24 h View Scheme

1: aq. NaOH / methanol / 6 h / 60 °C 2: 85 percent / DCC / dimethylformamide / 24 h View Scheme

1: H2, 1.0 M Na2CO3(aq.) / 5percent Pd/C / 3.5 h / 3102.9 Torr / Ambient temperature 2: tetrahydrofuran; diethyl ether / 1.) 1 h, ice cooled, 2.) 2 h, ambient temperature 3: 71 percent / N,N'-dicyclohexylcarbodiimide / dimethylformamide / 20 h / Ambient temperature View Scheme

1: 69 percent / 2 M NaOH / ethanol / 1.5 h / Heating 2: H2, 1.0 M Na2CO3(aq.) / 5percent Pd/C / 3.5 h / 3102.9 Torr / Ambient temperature 3: tetrahydrofuran; diethyl ether / 1.) 1 h, ice cooled, 2.) 2 h, ambient temperature 4: 71 percent / N,N'-dicyclohexylcarbodiimide / dimethylformamide / 20 h / Ambient temperature View Scheme

1: tetrahydrofuran; diethyl ether / 1.) 1 h, ice cooled, 2.) 2 h, ambient temperature 2: 71 percent / N,N'-dicyclohexylcarbodiimide / dimethylformamide / 20 h / Ambient temperature View Scheme

1: tetramethylguanidine / dimethylsulfoxide / 20 h / 50 °C 2: TFA / CH2Cl2 3: EDC / dimethylformamide / 40 °C 4: H2 / 5percent Pd/C / dimethylformamide / 2 h / 3102.9 Torr / Ambient temperature 5: 88 percent / DCC / dimethylformamide / 1.) 70 min, 0 deg C, 2.) 40 deg C, overnight 6: 1.) NaHCO3, 2.) HCl / H2O; dioxane / 1.) 15 min, ice-cooled, 2.) room temperature, overnight View Scheme

N-ethyl-N,N-diisopropylamine in N,N-dimethyl-formamide T=23°C; 18 h;

1: tetramethylguanidine / dimethylsulfoxide / 20 h / 50 °C 2: TFA / CH2Cl2 3: EDC / dimethylformamide / 40 °C 4: H2 / 5percent Pd/C / dimethylformamide / 2 h / 3102.9 Torr / Ambient temperature View Scheme