1.1: hydrogenchloride; water; phosphoric acid / 95 - 100 °C 1.2: 20 °C / pH 9 - 10 2.1: (2S,3S)-2,3-dihydroxybutanedioic acid / water / 1.5 h / 65 - 95 °C / Resolution of racemate 3.1: acetone / 5 °C / Reflux View Scheme

1.1: hydrogenchloride; water; phosphoric acid / 95 - 100 °C 1.2: 20 °C / pH 9 - 10 2.1: (2S,3S)-2,3-dihydroxybutanedioic acid / water / Resolution of racemate 2.2: 20 °C View Scheme

1.1: hydrogenchloride; water; phosphoric acid / 95 - 100 °C 1.2: 20 °C / pH 9 - 10 2.1: (2S,3S)-2,3-dihydroxybutanedioic acid / water / 1.5 h / 65 - 95 °C / Resolution of racemate 3.1: sodium methylate / toluene / 5 °C / Inert atmosphere; Reflux 3.2: 60 °C / Reflux View Scheme

1.1: hydrogenchloride; water; phosphoric acid / 95 - 100 °C 1.2: 20 °C / pH 9 - 10 2.1: (2S,3S)-2,3-dihydroxybutanedioic acid / water / 1.5 h / 65 - 95 °C / Resolution of racemate View Scheme

1: With hydrogenchloride; phosphoric acid; water T=95 - 100°C; 2: With sodium hydroxide in water T=20°C; pH=9 - 10; Product distribution / selectivity;