“…All the diastereomers and deoxy derivatives, except the 5-epimer, were found to be inactive, indicating that the integrity of three hydroxy groups in the sugar part are required to retain the activity.5) In contrast, the carbocyclic analogue showed herbicidal activity when applied to the foliage of weeds at 1000ppm. 4 ) On the other hand, the role of the spirohydantoin ring, which could be responsible for the interaction with a target site in plants, has not been clarified in spite of the synthesis of two analogues; a spirosuccinimide analogue,6) in which an amide nitrogen atom was replaced with a carbon atom, showed herbicidal activity, and a spirodihydrouracil analogue,7) in which a methylene group was inserted at the anomeric position, had no biological activity.…”