Synthesis And Herbicidal Activities Of Cyclic Imides Derivatives

Protoporphyrinogen oxidase (Protox) is a key enzyme in the chlorophyll and heme biosyhthetic pathway. This enzyme catalyzes the oxidation of protoporphyrinogenâ…¨to protoporphyrinâ…¨. It is the last common step in the production of heme and chlorophyll. Herbicides targeted to protox characteristically applied as foliar sprays, have a very rapid contact action, causing very rapid cellular collapse, desiccation of many troublesome weeds and growth inhibition. Exposure to light causes formation of singlet oxygen and other oxidative species, resulting in membrane disruption and subsequent cell death.The area of protox-inhibiting herbicide has been intensively investigated for over 40 years. In many respects, they appear to be ideal herbicides, because they are rapidly and do not harm mammals under normal conditions.In order to discover novel herbicides inhibiting protox with high efficacy, broad-spectrum activity, and safety to crops, three series of cyclic imides were designed and synthesized. They are N-substituted Phenyl -4,5,6,7-tetrahydro- isoindole -1,3 -dione, 3-alkoxy-N-substituted phenyl-2,3,4,5,6,7-hexahydro-isoindol-l-one and N-substituted Phenyl- 2,3,4,5,6,7-hexahydro-isoindol-1-one. Their structures were confirmed by ~1HNMR and elemental analyses, with some of them confirmed by the mass spectroscopy and X-ray crystallography in addition. Preliminary bioassay data showed that some of them possess excellent herbicidal activity. And the bioassay data also indicated that, for high inhibitory activity, N - substituted phenyl moiety are essential in these cyclic imides. Those compounds with substitution at para position by Cl and ortho position by F give relatively high activity.