2,4,4,6-tetrabromo-2,5-cyclohexadien-1-one; triphenylphosphine; calcium carbonate in 1,2-dichloro-ethane 3.5 h; Ambient temperature;

sodium hydride in N,N,N',N',N'',N''-hexamethylphosphoric triamide T=25°C; 10 h;

potassium fluoride; jones reagent in acetone T=0°C; 2 h;

1: 75 percent / 4-dimethylaminopyridin, triethylamin / CH2Cl2 / 23 h / Ambient temperature 2: 1.) sodium hydride 2.) HMPT / 1.) room temperature, THF 2.) room temperature for 16 h then 40 deg C for 2 h View Scheme

N,N,N',N',N'',N''-hexamethylphosphoric triamide; sodium hydride 1.) room temperature, THF 2.) room temperature for 16 h then 40 deg C for 2 h; Yield given. Multistep reaction;