1: 15.2 g / DCC / dimethylformamide / 1.) 0 deg C, 2 h; 2.) 7-8 deg C, overnight 2: 1.) NEt3; 2.) HOBt / 1.) DMF, 10 min; 2.) 7-8 deg C, overnight View Scheme

1: 75.5 percent / Et3N / H2O / Ambient temperature 2: 15.2 g / DCC / dimethylformamide / 1.) 0 deg C, 2 h; 2.) 7-8 deg C, overnight 3: 1.) NEt3; 2.) HOBt / 1.) DMF, 10 min; 2.) 7-8 deg C, overnight View Scheme

1: hydroxybenzotriazole, N-ethylpiperidine, DCC / DMF, 1) -10 to -5 deg C, 1 h; 2) r.t., overnight 2: 79 percent / α-chymotrypsin, H2O / methanol / 2 h / Ambient temperature; pH 9 3: 1) pentafluorophenol/DCC / 1) DMF, 4 h, r.t.; 2) 2 h, r.t. View Scheme

1: 79 percent / α-chymotrypsin, H2O / methanol / 2 h / Ambient temperature; pH 9 2: 1) pentafluorophenol/DCC / 1) DMF, 4 h, r.t.; 2) 2 h, r.t. View Scheme

2,3,4,5,6-pentafluorophenol; dicyclohexyl-carbodiimide 1) DMF, 4 h, r.t.; 2) 2 h, r.t.; Yield given. Multistep reaction;

benzotriazol-1-ol; triethylamine 1.) DMF, 10 min; 2.) 7-8 deg C, overnight; Yield given. Multistep reaction;

Multistep reaction;