Stereocontrolled Routes to 4-Methoxypentadienoates for Use in Natural Product Synthesis

Mild and efficient routes to (E,E)-and (E,Z)-4-methoxypentadienoic acid esters from readily accessible gamma,delta-epoxydienoates are described. The crucial epoxide methanolysis can be carried out in stereocomplementary ways by the use of either acid-mediated or palladium-catalysed procedures, the latter procedure proving preferable in most cases.