acetic anhydride; trifluoroacetic acid; zinc in tetrahydrofuran T=-25 - 18°C; 24 h;

1.1: 84 percent / zinc dust; acetic anhydride; trifluoroacetic acid / tetrahydrofuran / 24 h / -25 - 18 °C 2.1: lithium diisopropylamide*THF; quinine; water / toluene; cyclohexane / 21 h / 5 - 25 °C 2.2: 10.5 g / sulfuric acid / toluene / 4 h / 85 °C 3.1: 80 percent / 1-hydroxybenzotriazole; 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride / dimethylformamide; toluene / 18 h / 20 °C 4.1: hydrochloric acid / ethanol / 6 h / 20 °C 5.1: 5.44 g / NaOH / ethanol; 1-methyl-pyrrolidin-2-one / 10 h / 110 °C / pH 9 View Scheme