The Wittig Reaction. I. Synthesis of β,γ-Unsaturated Acids

Stereoselective Syntheses of β,γ-Unsaturated Esters and γ-Lactones: 1-(Benzotriazol-1-yl)-3-(diphenylphosphoryl)-1-ethoxy-1-propene, a Protected CCH2CO2Et Synthon Equivalent

“…The Wittig−Horner reaction has frequently been utilized for the preparation of α,β-unsaturated acids and their esters: it enables easy control of the geometry of the double bond by an appropriate choice of reagents and solvent, and the phosphorus reagents are readily available. − However, examples of the preparation of β,γ-unsaturated acids by the Wittig−Horner reaction are rare. , Janecki and Bodalski prepared β,γ-unsaturated amides via the aminolysis of β-(diethoxyphosphoryl)γ-lactones, themselves formed by reaction of deprotonated β-(diethoxyphosphoryl)propionic acid with a carbonyl compound followed by cyclization. However, direct reaction of β-(diethoxyphosphoryl)-substituted esters with carbonyl compounds normally occurs at the α-position to the ester group to give the α-[(diethoxyphosphoryl)methyl]-substituted acrylate derivatives , instead of β,γ-unsaturated esters because the α-proton in the β-(diethoxyphosphoryl)-substituted esters is more acidic than the β-proton.…”