- Site-Selective Late-Stage Aromatic [18F]Fluorination via Aryl Sulfonium Salts
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Site-selective functionalization of C?H bonds in small complex molecules is a long-standing challenge in organic chemistry. Herein, we report a broadly applicable and site-selective aromatic C?H dibenzothiophenylation reaction. The conceptual advantage of this transformation is further demonstrated through the two-step C?H [18F]fluorination of a series of marketed small-molecule drugs.
- Xu, Peng,Zhao, Da,Berger, Florian,Hamad, Aboubakr,Rickmeier, Jens,Petzold, Roland,Kondratiuk, Mykhailo,Bohdan, Kostiantyn,Ritter, Tobias
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supporting information
p. 1956 - 1960
(2019/12/24)
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- Selective removing method of benzene ring hydroxyl para-bromine and preparation method of dicamba
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The invention provides a selective removing method of benzene ring hydroxyl para-bromine. The method comprises following steps: a compound represented as formula (I) in the description is subjected toa reaction under the alkaline condition and the action of metal powder to remove hydroxyl para-bromine ions, and a compound represented as formula (II) in the description is obtained. The benzene ring hydroxyl para-bromine ions are selectively removed under the alkaline condition and the action of the metal powder, the reaction has higher selectivity, conversion rate and reaction rate are high, and a prepared product has higher purity.
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Page/Page column 5-7
(2019/06/05)
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- Preparation method of micamba methyl ester
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The invention provides a preparation method of micamba methyl ester. The preparation method comprises the steps as follows: A) salicylic acid and bromine are subjected to a reaction in concentrated sulfuric acid, 5-bromosalicylic acid is obtained; B) 5-bromosalicylic acid and chlorine are subjected to a chlorination reaction, 5-bromo-3,6-dichlorosalycylic acid is obtained; C) 5-bromo-3,6-dichlorosalycylic acid is subjected to a debromination reaction under the alkaline condition and under the action of metal powder, and 3,6-dichlorosalycylate is obtained; D) 3,6-dichlorosalycylate and halomethane are subjected to a methylation reaction in methanol and a quaternary ammonium salt phase transfer catalyst, and 3,6-dichloro-2-methyl methoxybenzoate is obtained; E) methanol is removed by distillation; F) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained. By means of the preparation method, the yield and purity are higher, the route is simple and the production cost is low.
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Paragraph 0077; 0080; 0081; 0084; 0085; 0088; 0089; 0092
(2019/06/13)
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- Continuous production processes of dicamba methyl ester and dicamba methyl ester emulsifiable concentrate
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The invention provides a continuous production process of dicamba methyl ester. The process comprises the following steps: A) 5-bromo-3,6-dichlorosalicylic acid is subjected to a reaction under an alkaline condition and under the action of metal powder to remove bromine atoms in para-positions of hydroxyl, and 3,6-dichlorosalicylic acid is obtained; B) 3,6-dichlorosalycylic acid and halomethane are subjected to an etherification reaction in a mixed solvent of water and methanol, and methyl 3,6-dichloro-2-methoxybenzoate is obtained; C) methanol is removed by distillation; D) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained. By means of the preparation process, continuous production can be realized, workers are notrequired to make direct contact with materials, the control degree is high, the production operation environment is greatly improved and safer, the process route and equipment are simple, the production cost is low, besides, the product yield and purity are greatly improved, and a superior route suitable for mass industrial production is provided.
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Paragraph 0074; 0077-0079; 0083-0086; 0089-0091
(2019/06/05)
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- Preparation method of dicamba
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The invention provides a preparation method of dicamba. The preparation method comprises the steps as follows: A) salicylic acid and bromine or hydrogen bromide are subjected to a reaction in concentrated sulfuric acid, 5-bromosalicylic acid is obtained; B) 5-bromosalicylic acid and chlorine are subjected to a chlorination reaction, 5-bromo-3,6-dichlorosalycylic acid is obtained; C) 5-bromo-3,6-dichlorosalycylic acid is subjected to a debromination reaction under the alkaline condition and under the action of metal powder, and 3,6-dichlorosalycylic acid is obtained; D) 3,6-dichlorosalycylic acid and halomethane are subjected to an etherification reaction in a mixed solvent of water and methanol, and methyl-3,6-dichloro-2-methoxybenzoate is obtained; E) methanol is removed by distillation;F) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained; G) dicamba methyl ester is subjected to alkaline hydrolysis, acidification and drying, and dicamba is obtained. The route comprises few steps and has low difficulty, the equipment requirement and investment are lower, continuous production can be realized, no three wastes are produced, and the product yield and purity are higher.
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Paragraph 0096; 0104; 0109; 0114; 0119; 0124; 0129; 0134
(2019/06/05)
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- A dicamba preparation method (by machine translation)
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The invention provides a method for preparing dicamba, comprises the following steps: A) 3, 6 - II [...] and halogenated methane in water and methanol in mixed solvent of the etherification reaction, to obtain 3, 6 - dichloro - 2 - methoxybenzoic acid methyl ester; B) distilled to remove the methanol; C) after the distillation system layered, organic phase distillation, to obtain baphia methyl ester; D) baphia methyl ester by the alkaline hydrolysis, acidification, drying, get baphia. The invention water and methanol mixed solvent as 3, 6 - II [...] etherification reaction solvent, reaction after first distilled to remove the methanol, then distillation baphia methyl ester, in order to distill and craft has replaced the traditional preparation method recrystallization process, and omits the decoloring this process, compared with the traditional process, the obtained baphia the color of the product is pure white, inch high, and improves the working environment on the site workers, more environment-friendly, alkaline hydrolysis process of the less water, the economical efficiency, technical and environmental protection, improves the stability of the product. (by machine translation)
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Paragraph 0041-0059
(2019/06/05)
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- Preparation method of dicamba
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The invention relates to a preparation method of dicamba. The method comprises the following steps: preparing 2, 5-dichlorobenzoic acid as a starting raw material; further esterifying with methyl alcohol in an acidic condition; processing to obtain a product; further substituting with bromine under the effect of aluminum tribromide; reacting the obtained product with methyl alcohol under the effect of a catalyst; processing; and further hydrolyzing the obtained product to obtain the final product, namely dicamba. Compared with a traditional synthesizing method, the method has the advantages that few synthesizing steps are performed; the reaction process is simple; the reaction temperature is low; the operation safety is improved; the reaction processing in each step is simple, so that thereaction can be conveniently carried out; and the yield is high.
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- 3,6-DICHLOROSALICYLIC ACID COMPOUNDS AND RELATED SYNTHETIC PROCESSES
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The present disclosure relates, in general, to 5-halo-3,6-dichlorosalicylic acid compounds, 5-halo-3,6-dichlorosalicyaldehyde compounds, processes for preparing 5-halo-3,6-dichlorosalicylic acid compounds, processes for preparing 5-halo-3,6- dichlorosalicyaldehyde compounds, processes for preparing 3,6-dichlorosalicylic acid compounds, and processes that employ such compounds as intermediates in the preparation of the herbicide dicamba.
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- Theoretical and experimental study on the reactivity of methyl dichlorobenzoates with sulfur-centered nucleophiles by electron transfer reactions
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Reactions of methyl 2,5-dichlorobenzoate or methyl 3,6-dichloro-2- methoxybenzoate with sulfur-centered nucleophiles gave mono- and disubstitution products, respectively through SRN1 mechanism in liquid ammonia. Products obtained could be potential herbicides less toxic to the environment. Theoretical studies explained the reactivity observed considering geometries, and spin densities of radical anions and potential energy surfaces for the dissociation of the radical anions formed.
- Uranga, Jorge G.,Monta?ez, Juan P.,Santiago, Ana N.
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body text
p. 584 - 589
(2012/02/05)
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- Trimethylstannylation of mono- and dichloroarenes by the SRN1 mechanism in liquid ammonia
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The photostimulated reaction of methyl 2,5-dichloro benzoate (1) or methyl 3,6-dichloro-2-methoxy benzoate (7) with -SnMe3 ions give good yields of the disubstitution products by the SRN1 mechanism in liquid ammonia. Conversely, in dark conditions, substrate 1 reacts with -SnMe3 ions to afford the mono-substitution products by the S RN1 mechanism. On the other hand, substrate 7 reacts with -SnMe3 ions in dark conditions to give mono-reduced product probably by a halogen metal exchange reaction. In addition, the photostimulated reaction of 2-chloro-N4-ethyl-N6- isopropyl-1,3,5-triazin-4,6-diamine (Atrazine, 11) with -SnMe 3 ions affords the reduced and substitution products in liquid ammonia-DMSO as co-solvent. Copyright
- Santiago, Ana N.,Basso, Silvana M.,Montanez, Juan P.,Rossi, Roberto A.
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p. 829 - 835
(2007/10/03)
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