Catalytic Ring Opening of Substituted 2-Oxetanones

Salts or complexes of Pd(II) promote the cleavage of the C-alkyl–oxygen bond (1–4 bond) of substituted 2-oxetanones 1 (β-lactones). In aprotic medium, 4-vinylic substituted 1 are isomerized to butadiene carboxylic acids 2 whereas in alcohol the addition of one molecule of solvent takes place. The overall process represents an easy synthetic route to unsaturated ether acids 3 or ether esters 4. The addition of ligands has a major effect both on the nature of the products formed and on the rate of the reactions. A mechanism involving the formation of unstable η3 allylic intermediates is proposed to account for the observed results. © 1976, American Chemical Society. All rights reserved.