1.1: sodium hydroxide / methanol; water / 12 h / 20 °C 1.2: pH 2 2.1: ammonia; sodium / tetrahydrofuran / 2.5 h / -70 °C / Inert atmosphere 2.2: ice / pH 3 3.1: diphenyl phosphoryl azide; triethylamine / benzene / 6 h / 80 °C 3.2: 30 h / 80 °C 4.1: palladium on carbon; chloroform; hydrogen / methanol / 24 h / 20 °C View Scheme