acetic anhydride T=20°C; 18 h;

TBBDA; acetic anhydride; sodium nitrite in dichloromethane T=0 - 5°C; 6 h;

1.1: lithium hydroxide hydrate / tetrahydrofuran; water / 2 h / 2 °C 1.2: 20 °C / pH 3 - 4 2.1: sodium nitrite / water / 0.33 h / 0 °C 3.1: acetic anhydride / 5 h / 100 °C View Scheme

1.1: sodium acetate / ethanol / Reflux 2.1: lithium hydroxide hydrate / tetrahydrofuran; water / 2 h / 2 °C 2.2: 20 °C / pH 3 - 4 3.1: sodium nitrite / water / 0.33 h / 0 °C 4.1: acetic anhydride / 5 h / 100 °C View Scheme

hydrogenchloride in ethyl acetate T=60°C; Ring cleavage; 0.25 h;

tetrabutyl ammonium fluoride in tetrahydrofuran T=20°C; 12 h; Sealed flask;