SYNTHESIS OF METHYL DL-JASMONATE

Reaction of pyrrolidine enamine (2) of methyl 2-oxocyclopentane-1-acetate (1) with 3-bromo-2-pentanone (5) in dioxane afforded methyl (±)-2-oxo-3-(1ʹ-ethyl-2ʹ-oxopropyl)cyclopentane-1-acetate (3) along with a small quantity of methyl (±)-2-oxo-3-(2ʹ-oxopentyl)cyclopentane-1-acetate (4). When, however, toluene was used as the solvent instead of dioxane, the major product was 4 and the minor one was 3. Intramolecular aldol condensation of 3 gave (±)-2-ethyl-6-methoxycarbonylmethylbicyclo[3.3.0]oct-1-en-3-one (7). Epoxydation of 7 followed by treatment with p-toluenesulfonylhydrazine gave methyl (±)-dehydrojasmonate (10). Restricted hydrogenation of 10 gave methyl di-jasmonate (11). © 1969, American Chemical Society. All rights reserved.