triethylamine; trifluoroacetic anhydride in dichloromethane T=0 - 20°C;

1.1: triethylamine; trifluoroacetic anhydride / dichloromethane / 0 °C 2.1: sodium hydrogencarbonate / methanol / 2 h / 70 °C / pH 6 / aq. phosphate buffer 3.1: benzotriazol-1-yloxyl-tris-(pyrrolidino)-phosphonium hexafluorophosphate; N-ethyl-N,N-diisopropylamine / dichloromethane / 0.17 h / 0 °C 3.2: 0 - 20 °C 4.1: trifluoroacetic acid / dichloromethane / 0 - 20 °C 5.1: benzotriazol-1-ol; N-ethyl-N,N-diisopropylamine; HATU / dichloromethane; acetonitrile 6.1: triethylsilane; trifluoroacetic anhydride / 2 h / 0 - 20 °C 7.1: triethylamine / dichloromethane / 3 h / 0 - 20 °C View Scheme