1: 82 percent / N-hydroxysuccinimide, N,N'-dicyclohexylcarbodiimide, NH3 / tetrahydrofuran / Ambient temperature 2: TFA / CH2Cl2 / 3 h / 0 - 20 °C 3: <bis(trifluoroacetoxy)iodo>benzene / acetonitrile; H2O / 3 h View Scheme

1: 82 percent / N-hydroxysuccinimide, N,N'-dicyclohexylcarbodiimide, NH3 / tetrahydrofuran / Ambient temperature 2: 46 percent / TFA / CH2Cl2 / 3 h / 0 - 20 °C 3: <bis(trifluoroacetoxy)iodo>benzene / acetonitrile; H2O / 3 h View Scheme

Multi-step reaction with 2 steps 1: 82 percent / N-hydroxysuccinimide, N,N'-dicyclohexylcarbodiimide, NH3 / tetrahydrofuran / Ambient temperature2: 46 percent / TFA / CH2Cl2 / 3 h / 0 - 20 °C  

With  sodium hydroxide in  ethanol 2 h;  Ambient temperature;   

With  1-hydroxy-pyrrolidine-2,5-dione; ammonia; dicyclohexyl-carbodiimide in  tetrahydrofuran  Ambient temperature;