Absolute configuration of 12‐Oxo‐10,15( Z )‐phytodienoic acid

12‐Oxo‐10,15( Z )‐phytodienoic acid biosynthesized from 13( S )‐hydroperoxy‐9( Z ),11( E ),15( Z )‐octadecatrienoic acid using a preparation of corn ( Zea mays L) hydroperoxide dehydrase recently was found to be a mixture of enantiomers in a ratio of 82∶18 (Hamberg, M., and Hughes, M.A. (1988) Lipids 23 , 469–475). In this work, 12‐oxophytodienoic acid and (+)‐7‐iso‐jasmonic acid were converted into a common derivative, methyl 3‐hydroxy‐2‐pentyl‐cyclopentane‐1‐octanoate. From gas liquid chromatographic analysis of the (−)‐menthoxycarbonyl derivative of methyl 3‐hydroxy‐2‐pentyl‐cyclopentane‐1‐octanoates prepared from 12‐oxophytodienoic acid and (+)‐7‐iso‐jasmonic acid, it could be deduced that the major enantiomer of 12‐oxophytodienoic acid had the 9( S ),13( S ) configuration. Therefore, in the major enantiomer of 12‐oxophytodienoic acid, the configurations of the side chainbearing carbons are identical to the configurations of the corresponding carbons of (+)‐7‐iso‐jasmonic acid, thus giving support to previous studies indicating that 12‐oxophytodienoic acid serves as the precursor of (+)‐7‐iso‐jasmonic acid in plant tissue.