PROSTAGLANDIN ENDOPEROXIDES .26. DECOMPOSITION OF LEVUGLANDIN-E2 - DEHYDRATION AND ALLYLIC REARRANGEMENT PRODUCTS

In aqueous solutions at 37 °C the β,γ-unsaturated 6-hydroxy aldehyde functional array in levuglandin E2 (LGE2) readily eliminates water to give an α,β,γ,6-unsaturated aldehyde, anhydro levuglandin E2 (AnLGE2), in competition with allylic prototropic shift to give an α,β,-unsaturated 6-hydroxy aldehyde, Δ9-LGE2. The allylic isomerization is catalyzed by H2P04-, 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 conditions examined (pH 2.8-8.0) and LGE2 is most stable at pH 34. © 1990, American Chemical Society. All rights reserved.