Wittig reaction
To obtain the ("E")-alkene for unstabilized ylides, the Schlosser modification of the Wittig reaction can be used. Alternatively, the Julia olefination and its variants also provide the ("E")-alkene selectively. Ordinarily, the Horner–Wadsworth–Emmons reaction provides the ("E")-enoate (α,β-unsaturated ester), just as the Wittig reaction does. To obtain the ("Z")-enoate, the Still-Gennari modification of the Horner-Wadsworth-Emmons reaction can be used.