1: With cinchonidine in acetonitrile Separation of racemate; 2: With hydrogenchloride in dichloromethane; water pH=2; Separation of racemate;

1: With sulfuric acid in 1,4-dioxane; water 2 h; Reflux; 2: With sodium hydroxide in 1,4-dioxane; water pH=12; 3: in 1,4-dioxane; water pH=3;

1.1: potassium hexamethylsilazane / tetrahydrofuran / 1.5 h / -25 - -15 °C / Inert atmosphere 1.2: -25 - 20 °C 2.1: cinchonidine / acetonitrile / Separation of racemate 2.2: pH 2 / Separation of racemate View Scheme

1.1: lithium hexamethyldisilazane; lithium chloride / tetrahydrofuran / 1 h / -5 °C 1.2: 3 h / -5 °C 2.1: sulfuric acid / 1,4-dioxane; water / 2 h / Reflux 2.2: pH 12 2.3: pH 3 View Scheme