Probing the role of the hydroxyl group of ABA: Analogues with a methyl ether at C-1′

Article abstract of DOI:10.1016/0031-9422(95)00781-4

(+)-(S)- and (-)-(R)-C-1′-O-methyl abscisic acids and their methyl esters, as well as the methyl ethers of the acetylenic analogue of methyl ABA, were synthesized through an enantioselective route, giving a series of optically active, new C-1′ substituted analogues with known stereochemistry. In a wheat embryo germination inhibition assay, (-)-C-1′-O-methyl ABA shows high activity, comparable with (+)- and (-)-ABA, whereas (+)-C-1′-O-methyl ABA is less active. In a wheat seedling transpiration assay, both analogues exhibit weak activity although the (+)-ABA-like analogue is more potent than its enantiomer. The anti-transpirant response increases over time, which may indicate that the analogue is being metabolized to ABA in vivo. Copyright