1: 78 percent / lead tetra-acetate / 1 h 2: toluene-p-sulphonic acid / CH2Cl2 / 1.5 h / Ambient temperature 3: 63 percent / H2 / 10percent palladized charcoal / tetrahydrofuran / Ambient temperature 4: 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 5: 1.) 2M aq. potassium hydroxide; 2.) sodium amalgam / 1.) tetrahydrofuran 20 deg C; 2.) 3-4 min 6: 0.5 h / coproporphyrinogen-III oxidase (from Euglena gracilis) View Scheme

sodium acetate; acetic acid; zinc in water T=65°C; 2 h;

1: acetoacetic acid tert-butyl ester With acetic acid; sodium nitrite T=5°C; 2: 3-(2-methoxycarbonyl-ethyl)-2,4-pentanedione With sodium acetate; acetic acid; zinc T=65°C;

acetic acid; sodium nitrite anschliessend Erwaermen mit 4-Acetyl-5-oxo-hexansaeure-methylester und Zink-Pulver;

1: 78 percent / lead tetra-acetate / 1 h 2: toluene-p-sulphonic acid / CH2Cl2 / 1.5 h / Ambient temperature 3: 63 percent / H2 / 10percent palladized charcoal / tetrahydrofuran / Ambient temperature 4: 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 5: 1.) 2M aq. potassium hydroxide; 2.) sodium amalgam / 1.) tetrahydrofuran 20 deg C; 2.) 3-4 min View Scheme

1: ammonium cerium (IV) nitrate 2: 3-chloro-benzenecarboperoxoic acid 3: trifluoroacetic acid; triethylsilane View Scheme