1: 3-(benzyloxy)cyclobutane-1-carboxylic acid With diphenyl phosphoryl azide; N-ethyl-N,N-diisopropylamine in toluene T=80°C; 7 h; Inert atmosphere; 2: potassium tert-butylate in tetrahydrofuran; toluene T=0 - 20°C; 1 h; Inert atmosphere;

diphenyl phosphoryl azide; triethylamine 20 h; Heating / reflux;

1.1: potassium hydroxide / ethanol; water / 0.75 h / Inert atmosphere; Reflux 1.2: pH 2 - 3 / Inert atmosphere 2.1: pyridine / 12 h / 120 °C 3.1: N-ethyl-N,N-diisopropylamine; diphenyl phosphoryl azide / toluene / 7 h / 80 °C / Inert atmosphere 3.2: 1 h / 0 - 20 °C / Inert atmosphere View Scheme

1.1: ethanol; sodium / 3 h / Inert atmosphere; Reflux 2.1: potassium hydroxide / ethanol; water / 0.75 h / Inert atmosphere; Reflux 2.2: pH 2 - 3 / Inert atmosphere 3.1: pyridine / 12 h / 120 °C 4.1: N-ethyl-N,N-diisopropylamine; diphenyl phosphoryl azide / toluene / 7 h / 80 °C / Inert atmosphere 4.2: 1 h / 0 - 20 °C / Inert atmosphere View Scheme

1.1: pyridine / 12 h / 120 °C 2.1: N-ethyl-N,N-diisopropylamine; diphenyl phosphoryl azide / toluene / 7 h / 80 °C / Inert atmosphere 2.2: 1 h / 0 - 20 °C / Inert atmosphere View Scheme

1.1: mercury dichloride / 18 h / 150 °C / Reflux; Inert atmosphere 2.1: ethanol; sodium / 3 h / Inert atmosphere; Reflux 3.1: potassium hydroxide / ethanol; water / 0.75 h / Inert atmosphere; Reflux 3.2: pH 2 - 3 / Inert atmosphere 4.1: pyridine / 12 h / 120 °C 5.1: N-ethyl-N,N-diisopropylamine; diphenyl phosphoryl azide / toluene / 7 h / 80 °C / Inert atmosphere 5.2: 1 h / 0 - 20 °C / Inert atmosphere View Scheme

hydrogen; palladium dihydroxide T=45°C; P=33753.4 Torr; 5 h;