requirement for the biologicalactivity of abscisicacid, the cyclopropane analogues 6, 7, 9, and 10 were synthesized and their biologicalactivities in four bioassays were tested. The activity of the achiralcyclohexadienoneanalogue 8 also was examined. Analogue 7 in which the 6′ β-substituent is constrained essentially to the axial-like orientation between axial and bisectional showed no activity, while 6
α-amylase induction and stomatal opening in spiderwort epidermal strip bioassays. (1′S)-(+)-1′-Deoxy-1′-fluoroabscisic acid showed 110 to 120 of the activity of (1′S)-(+)-ABA and was almost equal to (1′R)-(+)-1′-deoxyabscisic acid in these assays. These results suggest that the fluorine atom cannot mimic the C-1′ hydroxyl group. (1′R,6′S)-(+)-8′-fluoroabscisis acid was as effective as (+)-ABA, and the effect