trifluoroacetic acid in dichloromethane; toluene T=20°C; 1 h;

1: N-methyl-N-nosyl-L-leucine phenacyl ester With benzenethiol sodium salt in N,N-dimethyl-formamide T=20°C; 3 h; Inert atmosphere; 2: With sodium carbonate in water pH=9; 3: (9H-Fluoren-9-yl)-methyl chloroformate in 1,4-dioxane T=0°C;

1: With toluene-4-sulfonic acid in toluene 0.5 h; Heating; 2: With triethylsilane; trifluoroacetic acid in dichloromethane T=20°C; 24 h; Further stages.;

Multistep reaction.;

1: toluene-4-sulfonic acid / toluene / 24 h / Reflux; Azeotropic water removal 2: triethylsilane; AlCl3, aluminium chloride / dichloromethane / 1 h / 20 °C View Scheme