1: sulfuric acid 2: tin (II)-chloride; hydrochloric acid View Scheme

sulfuric acid in 1,4-dioxane; water T=100 - 105°C; 24 h;

1.1: triethylamine / methanol / 13 h / 50 - 55 °C / |Autoclave; |Large scale 2.1: water; sodium hydroxide / methanol / 3 h / 40 - 45 °C / |Autoclave; |Large scale 3.1: acetone / 57 °C / |Autoclave; |Large scale 4.1: hydrogenchloride / toluene; water / 20 °C / |Autoclave; |Large scale 4.2: 111 - 112 °C / |Large scale View Scheme

1.1: triethylamine / methanol / 13 h / 50 - 55 °C / |Autoclave; |Large scale 2.1: water; sodium hydroxide / methanol / 3 h / 40 - 45 °C / |Autoclave; |Large scale 3.1: acetone / 57 °C / |Autoclave; |Large scale 4.1: hydrogenchloride / toluene; water / 20 °C / |Autoclave; |Large scale 4.2: 111 - 112 °C / |Large scale 5.1: 5 palladium on charcoal; hydrogen / water; ethyl acetate View Scheme