2-FLUORO AND 2-METHOXYCARBONYL EPOXY-BETA-IONYLIDENEACETIC ACIDS AS ABSCISIC-ACID ANALOGS

Abscisic acid (ABA) is easily isomerized to inactive fl arts-ABA It li ght, To solve this problem, two variations of epoxy-beta-ionylideneace tic acid were synthesized as ABA analogs, each of them having a methox ycarbonyl or a fluoric substituent at the 2-position. The 2E-, and 2Z- fluorinated analogs showed moderate growth inhibitory activity toward rice seedlings and lettuce seeds, whereas the methoxycarbonyl analog w as inactive toward rice seedling growth and only partially active towa rd lettuce germination, The 2E-fluorinated analog was extensively isom erized to the 2Z-isomer bg UV irradiation, We think that a steric requ isite for the 2E-position was high, and that the fluorine substituent was not effective for fixing the 2-double bond in the E-configuration.