Excellent Herbicidal Activity Research Articles

Synthesis, herbicidal, fungicidal and insecticidal evaluation of 3-(dichlorophenyl)- isocoumarins and (±)-3-(dichlorophenyl)-3,4-dihydroisocoumarins

This is the first report showing that 3-(dichlorophenyl)isocoumarins and (±)-3,4-dihydroisocoumarins are plant and plant fungus growth inhibitors. 3-Dichlorophenylisocoumarins were synthesized by condensation of homophthalic acid with dichlorobenzoyl chlorides. The alkaline hydrolysis of these isocoumarins afforded keto acids. Racemic 3-(Dichlorophenyl)-3,4-dihydroisocoumarins were obtained by reduction of keto acids to racemic hydroxy acids, followed by cyclodehydration using acetic anhydride. The herbicidal, fungicidal and insecticidal activities of the synthesized compounds have been evaluated. Some of the synthesized compounds show excellent herbicidal and fungicidal activities but none of the synthesized compounds presented any insecticidal effects on the test insects. The findings of this study suggest that isocoumarins and related compounds may serve as lead compounds towards the design of bioactive herbicides and fungicides.

Synthesis of new bicyclo[4.1.0]heptane-2,4-dione derivatives and their herbicidal activity

Various triketone type 4-HPPD inhibitors were synthesized and their herbicidal activity and corn safety were evaluated. In the course of synthetic studies, we invented convenient methods to synthesize novel benzoyl-substituted bicyclo[4.1.0]heptanediones, and it was found that some showed excellent herbicidal activity against weeds in a corn field. Among these compounds, 3-(4-chloro-2-nitrobenzoyl)bicyclo[4.1.0]heptane-2,4-dione was found to be not only highly active against broadleaf weeds but also grass weeds, whereas it caused severe damage to corn. As a result of further efforts to modify benzoyl substituents, we found a compound, (1R*,6R*)-3-(2-chloro-4-methylsulfonylbenzoyl)bicyclo[4.1.0]heptane-2,4-dione, which provided a good combination of herbicidal activity and corn safety.

Herbicidal characteristics of MT-147, a novel glycol benzyl ether as a graminicide in paddy rice

The herbicidal performance of MT-147, (2R,3S,3aS,9bR)-2-ethyl-3-(2-fluorobenzyloxy)-6,7-methylenedioxy-3,3a,5,9b-tetrahydro-2H-furo[3,2-c][2]benzopyran, was examined as a graminicide for paddy rice. MT-147 completely controlled barnyardgrass from pre-emergence up to the 2.0-leaf stage at 300 g a.i./ha by submerged application; however, the efficacy decreased as the leaf stage proceeded further. The herbicidal activity of MT-147 was not influenced by water depth, but it was slightly affected by the seeding depth of barnyardgrass, the activity being lower when the seeding depth was deeper. MT-147 had no phytotoxicity to transplanted rice at 300 g a.i./ha but phytotoxicity was observed when rice seedlings were placed on the soil surface and the roots were exposed to water. Bromobutide remarkably increased the herbicidal activity of MT-147 against barnyardgrass. In this study, it was revealed that a novel 3,3a,5,9b-tetrahydro-2H-furo[3,2-c][2]benzopyran, MT-147, has excellent herbicidal activity against barnyardgrass, and its activity was enhanced by bromobutide.

Synthesis and Herbicidal Evaluation of Novel 3-[(α-Hydroxy-substituted)benzylidene]pyrrolidine-2,4-diones

A series of 3-[(alpha-hydroxy-substituted) benzylidene]pyrrolidine-2,4-dione derivatives were synthesized as candidate herbicides by reacting different aroyl acetates with N-substituted glycine esters. The new compounds were identified by 1H NMR spectroscopy and elemental analyses. Their herbicidal activities were evaluated. Some compounds exhibited excellent herbicidal activities at a dose of 187.5 g/ha. A suitable electron-donating substituent at the 2- and/or 4-position of the phenyl ring was essential for high herbicidal activity, a result that has not been reported before. It was also found that the title compound's structure-activity relationships were different from those of other similar kinds of earlier compounds, a result that may depend on the enol structure difference.

Synthesis and Herbicidal Activity of 2‐Cyano‐3‐(2‐fluoro‐5‐pyridyl)methylaminoacrylates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and herbicidal activity of 2-cyano-3-(2-fluoro-5-pyridyl)methylaminoacrylates

A series of 2-cyano-3-(2-fluoro-5 -pyridyl)methylaminoacrylates were synthesized as herbicidal inhibitors of photosystem II (PSII) electron transport. 2-Fluoro-5-pyridinemethylamine was prepared from 2-amino-5-methylpyridine, subsequent reaction with 2-cyano-3,3-dimethylthioacrylates or 2-cyano-3-methoxyacrylates to yield these title compounds. All of these compounds were confirmed by 1H NMR, IR, mass spectrum and elemental analyses. Their herbicidal activities were evaluated. All of the title compounds showed excellent herbicidal activities to amaranth pigweed and rape in post-emergence treatment. At the rate of 150 g/ha, one compound exhibited similar activity to Cl-analogue. The replacement of chlorine by fluorine group showed the same herbicidal activity.

Synthesis and herbicidal activity of 2-cyano-3-(2-chlorothiazol-5-yl)methylaminoacrylates.

A series of 2-cyano-3-(2-chlorothiazol-5-yl)methylaminoacrylates were synthesized as herbicidal inhibitors of PSII electron transport. All of these compounds exhibited good herbicidal activities. In particular, (Z)-ethoxyethyl 2-cyano-3-isopropyl-3-(2-chlorothiazol-5-yl)methylaminoacrylate showed excellent herbicidal activities even at a dose of 75 g/ha. A suitable group at the 3-position of acrylate was essential for high herbicidal activity. 2-Cyanoacrylates containing a 2-chloro-5-thiazolyl group are a novel class of herbicides and display herbicidal activities comparable to existing analogues bearing chloropyridyl or chlorophenyl.

Synthesis and Herbicidal Activity of Novel 3-Alkoxycarbonyl-3-aryl-2, 3-dihydro-2-oxo-1H-pyrrole Derivatives

In the course of efforts to find novel compounds with improved crop safety in transplanted rice by the modification of 1-[1-(3,5-dichlorophenyl)-1-methylethyl]-4-methyl-3-phenyl-3-pyrrolin-2-one (1a), which was reported to have excellent herbicidal activity against paddy weeds, 2,3-dihydro-2-oxo-1H-pyrrole derivatives with a quaternary carbon atom having an alkoxycarbonyl group at the α-position of the cyclic amide were synthesized and examined. Among these compounds, methyl 1-[1-(3,5-dichlorophenyl)-1-methylethyl]-2,3-dihydro-4-methyl-2-oxo-3-phenyl-1H-pyrrole-3-carboxylate (2a) was not only active against Echinochloa oryzicola and Scirpus juncoides but also compatible with transplanted rice even in harsh conditions. On the basis of preliminary experimental results, it was thought that 2a would generate the corresponding 2-oxo-3-pyrrolin (1a) through the metabolic degradation of the methoxycarbonyl moiety. © Pesticide Science Society of Japan

Synthesis and herbicidal activity of 2-cyano-3-substituted-pyridinemethylaminoacrylates.

Two series of 2-cyano-3-substituted-pyridinemethylaminoacrylates, namely 12 new (Z)-2-cyano-3-methylthio-3-substituted-pyridinemethaneaminoacrylates and 10 new (Z)-2-cyano-3-alkyl-3-substituted-pyridinemethaneaminoacrylates, were synthesized as herbicidal inhibitors of photosystem II (PSII) electron transport. All of these compounds were confirmed by (1)H NMR, elemental, IR, and mass spectrum analyses. Their herbicidal activities were evaluated. Some compounds exhibited excellent herbicidal activities, even at a dose of 75 g/ha. A suitable substituent at the 2-position of the pyridine ring and the well-fit group at the 3-position of acrylate were essential for high herbicidal activity. 2-Cyanoacrylates containing a substituted pyridine ring provide higher herbicidal activities than parent compounds containing phenyl. These PSII inhibitor herbicides are safe to corn, which is a major crop in China.

Synthesis and biological activity of novel cyanoacrylates containing ferrocenyl moiety

In a search for new herbicides with improved biological properties and different activity spectrum, we replaced phenyl moiety by ferrocenyl in cyanoacrylates, and synthesized a series of novel cyanoacrylates containing a ferrocene moiety by the reaction of aminomethylferrocene with ethoxyethyl 2-cyano-3-methylthioacrylate (or 2-cyano-3-alkoxyacrylates) in excellent yields. The title compounds were identified by IR, 1H-NMR spectroscopy, EI MS and elemental analyses. The results of bioassay showed that some title compounds exhibit excellent herbicidal activities. In general, we found that the replacement of the phenyl with ferrocenyl in cyanoacrylates still retained excellent herbicidal activities.

Synthesis and herbicidal activity of pyrimidine derivatives

A new class of 2-benzoylpyrimidines exhibited good pre- and post-emergence herbicidal activity at low rates. The selectivity and herbicidal activity were largely affected by the substituents on the phenyl and pyrimidine moieties. The compound having a trifluoromethyl group at the 4-position of the pyrimidine showed good selectivity toward soybean in pre-emergence treatment, while the compound having an isopropyl group showed excellent herbicidal activity against barnyardgrass in paddy field in post-emergence treatment. The structure–activity relationship and mode of action of this family of compounds are discussed. © 1999 Society of Chemical Industry

Herbicidal Activity of Derivatives Part II.

Eighty-nine O-aryl N-alkyl-N-arylcarbamates, mainly thiono-type thiocarbamates, were synthesized and their herbicidal and phytotoxic activities against barnyardgrass and rice plants, respectively, were evaluated under paddy field conditions to determine the relationship between chemical structure and the activity.The following points were clarified regarding herbicidal activity against barnyardgrass:1. In the phenoxy residue in aryl N-(6-methoxy-2-pyridyl)-N-methylcarbamates, condensed aryl groups such as 2-naphthyl, 5, 6, 7, 8-tetrahydro-2-naphthyl and 1, 4-methano-1, 2, 3, 4-tetrahydro-6-naphthyl showed excellent herbicidal activity.2. With regard to substituents on O-phenyl ring in O-phenyl N-(6-methoxy-2-pyridyl)-N-methyl-thiocarbamates, 3- or 4-substituted derivatives (meta or pare) showed higher activity than one other (ortho). Excellent herbicidal activity was shown by the alkyl groups, 3-isopropyl, 3-tert-butyl and 4-tert-butyl. As substituents other than the alkyl group, halogen and trifluoromethyl exhibited strong activity. From the results of structure-activity correlation analysis by adaptive least-squares method for substituents on O-phenyl ring, it was apparent that adequate hydrophobic and steric groups such as 3-iso-propyl, 3-tert-butyl and 4-tert-butyl are prefer-able for high activity.3. Among four types of carbamate of 4-tert-butylphenyl N-(6-methoxy-2-pyridyl)-N-methyl-carbamates, thiono-type thiocarbamate showed the highest activity, while carbamate was less active. Thiol-type thiocarbamate and dithiocarbamate exhibited no activity.4. In the N-alkyl group in O-3-tert-butylphenyl N-alkyl-N-(6-methoxy-2-pyridyl)-thiocarbamates, methyl group showed the highest activity.5. With regard to substituents on N-(2-pyridyl) ring in O-3-tert-butylphenyl N-methyl-N-(2-pyridyl) thiocarbamates, the highest activity was exhibited by 6-methoxy group.6. When N-phenyl group was introduced into O-3-tert-butylphenyl thiocarbamates, N-3-methoxyphenyl derivative showed almost the same high activity as 6-methoxy-2-pyridyl derivative.7. For highly active compounds, herbicidal activity against barnyardgrass at the 1.5 leaf stage was also examined, and O-3-tert-butylphenyl N-(6-methoxy-2-pyridyl)-N-methyl-thiocarbamate, pyributicarb, was found to be the most effective.

Development and Commercialization of New Herbicide Pyrazosulfuron-Ethyl

Pyrazosulfuron-ethyl (1) is a new rice herbicide discovered and commercialized by Nissan Chemical Ind., Ltd. Research and development were started by introduction of heterocyclic moieties into an existing sulfonylurea herbicide as a lead compound which showed excellent herbicidal activities. Extensive investigations suggested a potent herbicidal activity in pyrazole rings as the heterocyclic moiety which led to the discovery of pyrazosulfuron-ethyl. Development of new synthetic methods for intermediate pyrazolesulfonamides with various functional groups made it possible to investigate pyrazolesulfonylureas (Fig.3). Various new 3, 4 and 5-pyrazolesulfonamides were synthesized to obtain the pyrazolesulfonylureas including pyrazosulfuron-ethyl. Six synthetic methods for the important intermediate pyrazolesulfonamide 14 were also developed for manufucturing pyrazosulfuron-ethyl. In this paper these synthetic methods and a final step to pyrazosulfuron-ethyl are described.

新選択性除草剤キザロホップエチルの創製と工業化

Several derivatives of heterocyclic-oxy phenoxy propionic acid have been known as selective herbicides. During extensive investigations on this series with various condensed heterocyclic moieties, the quinoxalinyloxy phenoxy propionic acid derivatives were found to show an excellent herbicidal activity against grass weeds. Among them, ethyl 2- [4- (6-chloro-2-quinoxalinyloxy) phenoxy] propionate, (code No.NC-302, quizalofop ethyl) showed a potent herbicidal activity. It is commercialized as a novel post-emergence herbicide. In this paper, facile syntheses of substituted quinoxalines and quizalofop ethyl derivatives are described in detail.

RELATION BETWEEN STRUCTURE AND HERBICIDAL ACTIVITY OF SUBSTITUTED BENZOTHIADIAZOLES (2,1,3)

Summary. A large number of substituted benzothiadiazoles (2,1,3) was synthesized. In this report, the herbicidal activities of some halo‐ and alkyl‐substituted benzothiadiazoles (2,1,3) are described. It was found experimentally that at least one of the positions 5 and 6 in the molecule must be unsubstituted. Some di‐ and tri‐substituted derivatives had excellent herbicidal activities, in contrast to tetra‐substituted benzothiadiazoles (2,1,3). Relation entre la structure et I'activité herbicide des (2,1,3) benzothiadiazoles substitués