in toluene 8 h; Reflux;

1: n-butyllithium / tetrahydrofuran; hexane / -42 °C / Inert atmosphere 2: tetrahydrofuran; hexane / -42 - 20 °C / Inert atmosphere 3: 2,2,6,6-tetramethyl-piperidine-N-oxyl; [bis(acetoxy)iodo]benzene / water; acetonitrile / 7 h / 20 °C 4: trifluorormethanesulfonic acid / 1,2-dichloro-ethane / 18 h / Reflux View Scheme

1: 1-hexyl-triphenylphosphonium bromide With sodium amide in tetrahydrofuran 1 h; Heating; 2: trans-4-oxo-but-2-enoic acid methyl ester in tetrahydrofuran Wittig reaction; 1 h; Title compound not separated from byproducts;

1: 1-hexyl-triphenylphosphonium bromide With sodium amide in tetrahydrofuran 1 h; Heating; 2: trans-2,4-pentadienal in tetrahydrofuran T=-10 - 0°C; Wittig reaction; 1 h; Further stages. Title compound not separated from byproducts.;

1: 1) sodium bis(trimethylsilyl)amide / 1) toluene, THF, r.t., 30 min, 2) toluene, -78 deg C, 30 min 2: 82 percent / TiCl4 / CH2Cl2 / 2 h / -78 °C 3: 92 percent / Et3N / CH2Cl2 / 1 h / Ambient temperature 4: 80 percent / CdCO3, HgCl2, CH3I, water / acetone / 4 h / Ambient temperature 5: 74 percent / piperidine / acetonitrile / 8 h / Ambient temperature 6: 95 percent / Et3N, 4-dimethylaminopyridine / CH2Cl2 / 4 h / Ambient temperature 7: 76 percent / Pd(Ph3P)4, Et3N / tetrahydrofuran / 3 h / Heating 8: 85 percent / aluminum hydride / tetrahydrofuran / 2 h / 0 °C 9: 38 percent / PPh3, CBr4 / CH2Cl2 / 0.5 h / -10 °C 10: 80 percent / acetonitrile / 2 h / Ambient temperature 11: 1) BuLi, 2) HMPA / 1) hexane, THF, -78 deg C, 20 min, 2) THF a) -78 deg C, 20 min, -40 deg C, 30 min 12: 92 percent / Bu4NF / tetrahydrofuran / 4 h / Ambient temperature 13: potassium carbonate, water / methanol / Ambient temperature View Scheme

potassium tert-butylate in tetrahydrofuran

1: 1) <(CH3)3Si>2NNa / 1) THF, reflux, 2 h, 2) -78 deg, 1 h, 3) room temperature, 10 h 2: 73 percent / 10percent aq. HCl / acetone / 3 h / 20 - 23 °C 3: 55 percent / diethyl ether / 1) 0 deg C, 30 min, 2) 20-25 deg C, 4 h 4: 77 percent / pyridinium chlorochromate / CH2Cl2 / 6 h View Scheme

sodium hexamethyldisilazane in diethyl ether T=-78°C; Yield given. Yields of byproduct given;

1: n-butyllithium / tetrahydrofuran; hexane / -42 °C / Inert atmosphere 2: tetrahydrofuran; hexane / -42 - 20 °C / Inert atmosphere 3: 2,2,6,6-tetramethyl-piperidine-N-oxyl; [bis(acetoxy)iodo]benzene / water; acetonitrile / 7 h / 20 °C 4: trifluorormethanesulfonic acid / 1,2-dichloro-ethane / 18 h / Reflux View Scheme

in dimethyl sulfoxide; Petroleum ether