A new oxidativesubstitutionreaction where an organotin group is replaced by an acetoxy group has been investigated; this reaction has been successfully applied to the synthesis of 4-ylidenebutenolides.
A New, Highly Stereoselective Synthesis of β-Unsubstituted (<i>Z</i>)<i>-</i>γ-Alkylidenebutenolides Using Bromine as a Removable Stereocontrol Element
Several β-unsubstituted (Z)-γ-alkylidenebutenolides have been prepared in highly stereocontrolled fashion by implementing a steric directing group stratagem in the vinylogous aldol condensation of butenolides with aldehydes. Applications to the synthesis of the antitumor heptene (S)-melodorinol and a thiophenelactone from Chamaemelum nobile L. are described.
5-Substituted 2-tributylstannylfurans which were synthesized by the reaction of corresponding 5-substituted 2-lithiofurans with tributylstannyl chloride, were treated with two equimolar amounts of lead tetraacetate at room temperature to give corresponding 5-substituted 5-acetoxy-2(5H)-furanones in good yields. The 5-acetoxy-2(5H)-furanone was heated at 80 °C in acetic acid-acetic anhydride containing