Résumé
2-(2-Tetrahydrofurylidene)propionates, usually obtained only in the more stable (E) configuration 1, were efficiently isomerised into their (Z) isomers 2 by use of Lewis acids or metallated bases. The (E)/(Z) isomerisation was governed by different factors (type of chelating agent, nature and steric demand of the α,β-unsaturated group). We demonstrated that judicious selection of the α,β-unsaturated group, in combina