Broadleaf weed activity

Alkylation of the nitrogen atom renders the molecule inactive. N-(Acetoxymethylation) retains preemergent activity while increasing postemergent broadleaf weed activity over that of the parent. Being derivatives of formaldehyde, these hemiaminals hydrolyze readily in soil and plant to the active parent NH-compound. 

Sugar herbicide RE 39571, 5,6-dideoxy-l,2-0-(l-methylethylidene)-3-0-(2-methylphenylmethyl)-a-D-xylo-hexofuranose (Figure 1), a representative of a novel series of chiral grass herbicides, has been demonstrated in our laboratories to possess a high level of preemergence herbicidal activity against grassy weeds with safety on soybeans, cotton, peanuts, and several other broadleaf crops. This herbicide has also been demonstrated to possess some broadleaf weed activity. 

BEST BROADLEAF WEED ACTIVITY AND EXCELLENT MULTICROP SELECTIVITY WHEN R = NHSOpEt... 

G-32911, simetryn Simetryn was one of the first methylthiotriazine candidates tested, but was developed slowly until it was confirmed that rice had a higher crop tolerance to simetryn than to prometryn. It found its commercial place in the transplanted rice of Japan and in other countries in the subtropical rice belt. Simetryn is used to control broadleaf weeds in mixtures with other herbicides that are active against grasses. 

The chlorophenoxy compounds 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) may be the most familiar herbicides. They have been used in agriculture (to eradicate broadleaf weeds) and to control woody plants in ditches and along highways. They act as growth hormones in many plants, and can evoke active plant growth in areas in which abnormal, twisted, or curtailed growth occurs. Massive doses... 

Structure-activity studies have shown the crucial role of the trifluoromethyl group in optimum biological activity of bleaching herbicides [38], Isoxaflutole (Balance , Merlin ) is a root or foliar uptake systemic herbicide with broad-spectrum control in corn and sugarcane of both grass and broadleaf weeds [39], Isoxaflutole is rapidly converted in plants and in soil to the diketonitrile form, which is the biologically active species (Fig. 7) [40],... 

Another example of a trifluoromethyl heteroaryl-containing herbicide is di-thiopyr (Dimension ) [72], Structure-activity studies have demonstrated that a fluorinated alkyl group is required for optimum activity at the 2 and/or 6 positions of the pyridine ring [73], Thiazopyr (Mandate , Visor ), a herbicide related to dithiopyr, was introduced by Monsanto in 1992 and later sold to Rohm and Haas. It is used for the pre-emergence control of annual grass and a few broadleaf weeds in tree fruit, vines, sugar cane, and other crops. 

Uses Glyphosate is a phosphanoglycine and does not inhibit cholinesterase activity.12,13 Glyphosate is a broad-spectrum, nonselective systemic herbicide with moderate toxicity. Essentially, it is useful on all annual and perennial plants including grasses, sedges, broadleaf weeds, and woody plants. It is used on noncropland and on a variety of crops.17,28-34... 

Evaluation of TFMS Herbicidal Activity. The herbicidal potency of the 15 substituted TFMS compounds was rated after a 21-day test period on a 0-100% kill scale. Herbicidal test data were collected for two grass species (Foxtail, Cheat Grass) and a broadleaf weed (Wild Mustard) in the presence and absence of 0.1% (w/v) Tween 80. Since the tests... 

Thus, it seems that the anomalous methylthio-TFMS herbicidal activity we have observed in our structure-activity studies on grass and broadleaf weeds is attributable to in vivo conversion of the -SCH3 side chain to more highly oxidized forms (-SOCH3, -S02CH3). Alternatively, methylthio-TFMS derivatives may function herbicidally via a completely different mode of action than the other TFMS derivatives examined. In light of the arguments presented, however, this seems to be a much less likely possibility than the in vivo oxidation proposal. 

Unsubstituted uracils have no herbicidal activity but certain derivatives substituted in the 3,5,6-positions are active. The most important examples are bromouracil, terbacil, and lenacil. These compounds were introduced by DuPont in 1963. These herbicides are applied to the soil and are used for selective weed control. Bromacil and terbacil are pre- and postemergence herbicides they control a wide spectrum of grass and broadleaf weeds when applied early in the growing season. These compounds must be carried to the roots by soil moisture, where they are absorbed and translocated to the rest of the plant. This family of herbicides is used for asparagus, sugar cane, pineapple, apple, and citrus crops. 

We first became interested in pyridazines as herbicides when a number of pyridazines synthesized in a CNS project at our Lederle division were evaluated in our primary herbicide screen. One of these compounds, AC 228,764, controlled eleven of the twelve weed species at 8 kg/ha in the preemergence test. All of the test species were bleached, emerging white from the soil. In our secondary evaluation at 4 kg/ha, AC 228,764 controlled ten out of eleven annual grass and broadleaf weed species with selectivity in cotton, soybeans and rice. This spectrum of activity and crop... 

Synthetic studies focused on the bicyclic heterocycle led to the discovery of a new sub-class of sulfonamides where the triazolo[l,5-a]pyrimidine ring was replaced with a triazolo[l,5-c]pyrimidine ring. Further investigations led to the development of diclosulam (3) and cloransulam-methyl (4) for broadleaf weed control in soybeans, and florasulam (5) for broadleaf weed control in cereals. To fully explore this sub-class of sulfonamides, an investigation was initiated to determine if reversing the sulfonamide linkage (6) would lead to compounds with the spectrum of activity on weeds and crop selectivity different from 3, 4, and 5. 

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