1: fmoc-O-tert-butyl-L-tyrosine With benzotriazol-1-ol; N-ethyl-N,N-diisopropylamine; diisopropyl-carbodiimide in N,N-dimethyl-formamide 0.25 h; 2: in N,N-dimethyl-formamide 3: Fmoc-Arg (Boc)2-OH; N-(fluoren-9-ylmethoxycarbonyl)-L-Val; N-(9-fluorenylmethoxycarbonyl)-L-aspartic acid-β-(tert-butyl)ester; N-(fluoren-9-ylmethoxycarbonyl)-L-Lys(Nε-Boc) Further stages;

1: N-ethyl-N,N-diisopropylamine; diisopropyl-carbodiimide; HONB / neat (no solvent) / 0.25 h / 60 °C / |Microwave irradiation; |Green chemistry 2: hydrogenchloride / water / 0.25 h / 25 °C 3: potassium carbonate / ethanol / 1 h / 25 °C 4: palladium 10 on activated carbon; ammonium formate / ethanol / 10 h / 60 °C View Scheme

1: hydrogenchloride / water / 0.25 h / 25 °C 2: potassium carbonate / ethanol / 1 h / 25 °C 3: palladium 10 on activated carbon; ammonium formate / ethanol / 10 h / 60 °C View Scheme

1: 92 percent / Cs2CO3 2: catalytic transfer hydrogenation View Scheme

1: fmoc-O-tert-butyl-L-tyrosine With benzotriazol-1-ol; N-ethyl-N,N-diisopropylamine; diisopropyl-carbodiimide in N,N-dimethyl-formamide 1 h; solid phase reaction; 2: With piperidine in N,N-dimethyl-formamide 0.5 h; solid phase reaction; 3: N-(fluoren-9-ylmethoxycarbonyl)-L-Val; N-(9-fluorenylmethoxycarbonyl)-L-aspartic acid-β-(tert-butyl)ester; N-(fluoren-9-ylmethoxycarbonyl)-L-Lys(Nε-Boc); N-α-Fmoc-N-ω,N-ω'-bis-tert-butoxycarbonyl-L-arginine Further stages;

methyl-phenyl-thioether; hydrogen fluoride; methoxybenzene; ortho-cresol 0.5 h; ice bath;

1: HOBT, dicyclohexylcarbodiimide 2: TFA-anisole 3: HOBT-dicyclohexylcarbodiimide 4: TFA-anisole 5: HOBT-dicyclohexylcarbodiimide 6: TFA-anisole 7: HOBT, dicyclohexylcarbodiimide 8: HF, anisole-thioanisole-o-cresol / 0.5 h / ice bath View Scheme

1: HOBT-dicyclohexylcarbodiimide 2: TFA-anisole 3: HOBT-dicyclohexylcarbodiimide 4: TFA-anisole 5: HOBT, dicyclohexylcarbodiimide 6: HF, anisole-thioanisole-o-cresol / 0.5 h / ice bath View Scheme

1: HOBT, dicyclohexylcarbodiimide 2: TFA-anisole 3: HOBT-dicyclohexylcarbodiimide 4: TFA-anisole 5: HOBT-dicyclohexylcarbodiimide 6: TFA-anisole 7: HOBT, dicyclohexylcarbodiimide 8: HF, anisole-thioanisole-o-cresol / 0.5 h / ice bath View Scheme

1: TFA-anisole 2: HOBT-dicyclohexylcarbodiimide 3: TFA-anisole 4: HOBT-dicyclohexylcarbodiimide 5: TFA-anisole 6: HOBT, dicyclohexylcarbodiimide 7: HF, anisole-thioanisole-o-cresol / 0.5 h / ice bath View Scheme