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Synthesis and characterisation of some 4‐keto derivatives of 1,3,4(2 H )‐isoquinolinetrione redox mediator herbicides
Author(s) -
Mitchell Glynn,
Clarke Eric D,
Ridley Stuart M,
Gillen Kevin J,
Vohra Shaheen K,
Greenhow Daren T
Publication year - 2000
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/(sici)1526-4998(200002)56:2<127::aid-ps113>3.0.co;2-l
Subject(s) - oxime , imine , chemistry , redox , photosystem ii , hydrazone , hydrolysis , cyclic voltammetry , stereochemistry , medicinal chemistry , organic chemistry , photosynthesis , electrochemistry , biochemistry , catalysis , electrode
Abstract Derivatives of 2‐ethyl‐1,3,4( 2H )‐isoquinolinetrione in which the 4‐keto group has been modified to ( Z )‐oxime, ( E )‐ and (Z)‐O ‐methyl oxime, (Z)‐N,N ‐dimethyl hydrazone, cyano‐imine and dicyanomethylene moieties have been prepared and evaluated as redox mediator herbicides. All of the compounds have the free‐radical properties required to function as redox mediators, as determined by cyclic voltammetry, though only the O ‐methyl oximes, the N,N ‐dimethyl hydrazone and the cyano‐imine have reduction potentials in the range required to stimulate the light‐dependent consumption of oxygen at photosystem I in isolated chloroplasts. The O ‐methyl oximes and the cyano‐imine are fast‐acting post‐emergence herbicides, producing symptoms of rapid desiccation; the (E)‐O ‐methyl oxime is the most active herbicide, being somewhat more potent than the parent isoquinolinetrione. Hydrolysis studies indicate that it is unlikely that any compound generates the parent isoquinolinetrione in vivo . Attempts to explain differences between in vitro and in vivo activities using hydrolytic stabilities and physical properties were unsuccessful, and it was concluded that these factors probably play a less significant role in moderating the herbicidal activity of isoquinolinetrione derivatives than originally thought. © 2000 Society of Chemical Industry