1: With methanol; methanesulfonic acid T=50 - 70°C; 0.75 h; 2: With potassium hydroxide in methanol; water T=22 - 70°C; 43 h; 3: in water T=50°C; 41 h; Product distribution / selectivity;

1.1: 38 °C 2.1: 3,4-dihydro-3-hydroxy-4-keto-1,2,3-benzotriazine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 20 °C 2.2: 20 °C 3.1: hydrogenchloride / ethyl acetate View Scheme

1.1: 3,4-dihydro-3-hydroxy-4-keto-1,2,3-benzotriazine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 20 °C 1.2: 20 °C 2.1: hydrogenchloride / ethyl acetate View Scheme

1.1: triethylamine; 3,4-dihydro-3-hydroxy-4-keto-1,2,3-benzotriazine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 3 h / 38 °C / |Inert atmosphere; |Large scale 2.1: sodium hydroxide / water; tert-butyl methyl ether / 20 °C / |Large scale 3.1: 3,4-dihydro-3-hydroxy-4-keto-1,2,3-benzotriazine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 20 °C 3.2: 20 °C 4.1: hydrogenchloride / ethyl acetate View Scheme

1: 1-hydroxy-7-aza-benzotriazole; 4-methyl-morpholine; N,N-dimethyl acetamide; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride 2: hydrogenchloride / ethyl acetate 3: 1-hydroxy-7-aza-benzotriazole; 4-methyl-morpholine; N,N-dimethyl acetamide; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride 4: hydrogenchloride / ethyl acetate View Scheme