Synthesis of Racemic [2-C]Jasmonic Acid*

Jasmonic acid [(l^?5',27?5')-3-oxo-2-(2Z-pentenyl)cyclopentane-1-acetic acid] (4)* (Fig. 1) and its methyl ester are not only important substances in perfumery but the (-)-enantiomer of 4 and (-)-methyl jasmonate are also known to be endogenous plant growth regulators, widely distributed within the plant kingdom, and possessing phytohormone like properties [2, 3], Both substances have received particular attention because of their physiological effects, like growth inhibition in rice seedlings, promotion of senescence in detached oat leaves, and inhibition of pollen germination etc. (for detailed references see [3, 4]). Senescence promotion by JA-Me in barley leaves is accompanied with degradations of chlorophyll and ribulose-l,5-bisphosphate carboxylase [5] and the induction of new polypeptides [6]. Further clarification of the physiological role of JA depends at least partly on the availability of radiolabeled JA for studies on uptake, transport, and metabolism in plants. Radiolabelled (±)-JA has been prepared by catalytic tritium exchange [7], (±)-[2-C]9,10-dihydro-JA has also been synthesized [8]. The present paper describes a simple two step synthesis for (±)-[2-C]JA. Materials and Methods