1: 60 percent / trimethyl orthoformate / trifluoroacetic acid / 0.37 h / 0 °C 2: 58 percent / 1.) trifluoroacetic acid, 2.) sodium acetate / methanol; CH2Cl2 / 1.) 2-3 deg C 90 min, 2.) 18 deg C 5 min, 3.) 50 min 3: 1.) 2M aq. potassium hydroxide; 2.) sodium amalgam / 1.) tetrahydrofuran 20 deg C; 2.) 3-4 min 4: 0.5 h / coproporphyrinogen-III oxidase (from Euglena gracilis) View Scheme

1.1: trifluoroacetic acid / 1.17 h / 0 °C / Inert atmosphere 1.2: 0 - 5 °C / Inert atmosphere 2.1: trifluorormethanesulfonic acid; acetic anhydride; acetic acid / 1 h / 20 °C / Inert atmosphere 3.1: sodium tetrahydroborate / methanol; dichloromethane / 1.33 h / 20 °C / Inert atmosphere View Scheme

1: 60 percent / trimethyl orthoformate / trifluoroacetic acid / 0.37 h / 0 °C 2: 58 percent / 1.) trifluoroacetic acid, 2.) sodium acetate / methanol; CH2Cl2 / 1.) 2-3 deg C 90 min, 2.) 18 deg C 5 min, 3.) 50 min 3: 1.) 2M aq. potassium hydroxide; 2.) sodium amalgam / 1.) tetrahydrofuran 20 deg C; 2.) 3-4 min View Scheme