Enantioselective Horner–Wadsworth–Emmons reaction for the asymmetric synthesis of α-fluoro-α,β-unsaturated esters

The enantioselective Horner–Wadsworth–Emmons reaction of 2-fluoro-2-diethylphosphonoacetates with σ-symmetric prochiral 2-substituted-1,3-dioxan-5-ones and 4-substituted-cyclohexanones was investigated by employing Sn(OSO2CF3)2 and N-ethylpiperidine in the presence of an external chiral ligand, (S)-(−)-1-methyl-2-(1-piperidinomethyl)pyrrolidine. A chiral α-fluoro-α,β-unsaturated ester was obtained in up to 80% ee.