in acetic acid 63 h; Ambient temperature;

1: K2CO3 / dimethylformamide / 6 h / 20 °C 2: 43 percent / Br2; NaOMe / 0.5 h / Heating View Scheme

1: (S)-9-(allyloxy)-8-[bis((tert-butoxy)carbonyl)amino]-9-oxonon-4-enoic acid With benzotriazol-1-ol; O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate; N-ethyl-N,N-diisopropylamine in dichloromethane; N,N-dimethyl-formamide 24.5 h; Inert atmospheresolid phase reaction; 2: With trifluoroacetic acid in dichloromethane 1.08333 h; solid phase reaction; 3: N-Boc-N,O-dimethyl-3-bromotyrosine; N2-[(1,1-Dimethylethoxy)carbonyl]-L-glutamine; N-(fluoren-9-ylmethoxycarbonyl)-L-Val; fmoc-L-Ile-OH; N-Fmoc-L-threonine-OH; Fmoc-citrulline; butyric acid Further stages;

1: 70.6 percent / bis(trifluoroacetoxy)-phenyliodine; N,N-diisopropylethylamine / acetonitrile; H2O / 20 °C 2: 79.5 percent / NaHCO3 / H2O; dioxane / 2 h / 20 °C View Scheme

1: [bis(trifluoroacetoxy)iodo]benzene; pyridine / dimethylformamide; H2O 2: Basic condition View Scheme

4-(N,N-dimethlyamino)pyridine; triethylamine in acetonitrile T=20°C; 0.75 h;

dicyclohexyl-carbodiimide

sodium tetrahydroborate; triethylamine; isobutyl chloroformate 1.) THF, -10 deg C, 2.) water, 0 deg C, 1 h; Yield given. Multistep reaction;

benzotriazol-1-ol; N'-(3-dimethylaminopropyl)-N-ethylcarbodiimide in dichloromethane; N,N-dimethyl-formamide 3 h;

[bis(acetoxy)iodo]benzene in tetrahydrofuran; water T=4°C; Hofmann reaction; 6 h;