in tetrahydrofuran 1 h;

1: tetrahydrofuran / 1.75 h / 20 °C / |Large scale 2: triethylamine / dichloromethane / 3 h / |Large scale 3: pyridine / 18 h / 10 - 20 °C 4: caesium carbonate / 1-methyl-pyrrolidin-2-one / 16 h / 60 °C / |Large scale 5: trifluoroacetic acid / dichloromethane / 4.17 h / -2 - 20 °C / |Large scale 6: N-ethyl-N,N-diisopropylamine; 1-propanephosphonic acid cyclic anhydride / dichloromethane / 18 h / 12 - 44 °C / |Large scale View Scheme

Multi-step reaction with 5 steps 1: tetrahydrofuran / 1.75 h / 20 °C / |Large scale2: triethylamine / dichloromethane / 3 h / |Large scale3: pyridine / 18 h / 10 - 20 °C4: caesium carbonate / 1-methyl-pyrrolidin-2-one / 16 h / 60 °C / |Large scale5: trifluoroacetic acid / dichloromethane / 4.17 h / -2 - 20 °C / |Large scale  

Multi-step reaction with 3 steps 1: tetrahydrofuran / 1.75 h / 20 °C / |Large scale2: triethylamine / dichloromethane / 3 h / |Large scale3: pyridine / 18 h / 10 - 20 °C  

Multi-step reaction with 4 steps 1: tetrahydrofuran / 1.75 h / 20 °C / |Large scale2: triethylamine / dichloromethane / 3 h / |Large scale3: pyridine / 18 h / 10 - 20 °C4: caesium carbonate / 1-methyl-pyrrolidin-2-one / 26 h / 60 °C / |Large scale