Decomposition of Levuglandin E2. Dehydration and Allylic Rearrangement Products

Article abstract of DOI:10.1021/jo00297a037

In aqueous solutions at 37 deg C the β,υ-unsaturated δ-hydroxy aldehyde functional array in levuglandin E₂ (LGE₂) readily eliminates water to give an α,β,γ,δ-unsaturated aldehyde, anhydro levuglandin E₂ (AnLGE₂), in competition with allylic prototropic shift to give an α,β-unsaturated δ-hydroxy aldehyde, Δ⁹-LGE₂.The allylic isomerization is catalyzed by H2PO4^-, perhaps by a bifunctional mechanism involving both proton acceptance by and donation from the catalyst.Thus, by appropriate adjustment of buffer concentration, the product distribution can be altered in a synthetically useful manner.Unexpectedly, the dehydration is not catalyzed by acid under the conditionsexamined (pH 2.8-8.0) and LGE₂ is most stable at pH 3-4.