Synthesis of Ethyl dl-Jasmonate and Ethyl dl-2-Epi-jasmonate

Ethyl dl-jasmonate (1a) and ethyl dl-2-epi-jasmonate (1b), novel constitutents in jasmin absolute from Italian Jasminum grandiflorum L, were prepared from 8-endo-(2'-cis-pentenyl)-3-oxo-2-oxa-bicyclo [3.2.1] octane, jasmine acid δ-lactone(2). Improvement of the preparation of the intermediate (9), a key precursor of (2), was made by different route via lactonization of (7) and/or (8). NMR and IR spectra (la) and (1b) are given.