A one-pot synthesis of (E)-α-bromo-α,β-unsaturated esters and their trifluoromethylation: a general and stereoselective route to (E)-α-trifluoromethyl-α,β-unsaturated esters

Bromination of a phosphonate anion derived in situ from ethyl bis(2,2,2-trifluoroethyl)phosphonoacetate 3 followed by the addition of aldehydes produced (E)-α-bromo-α,β-unsaturated esters 5 stereoselectively. The treatment of 5 with FSO2CF2CO2Me and CuI in DMF/HMPA provided (E)-α-trifluoromethyl-α,β-unsaturated esters 6.