- DIFLUOROMETHOXYLATION AND TRIFLUOROMETHOXYLATION COMPOSITIONS AND METHODS FOR SYNTHESIZING SAME
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The present invention provides a compound having the structure (I), a processing of making the compound; and a process of using the compound as a reagent for the difluoromethoxylation and trifluoromethoxylation of arenes or heteroarenes.
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Page/Page column 75; 79; 89; 102-103
(2019/09/18)
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- Catalytic radical difluoromethoxylation of arenes and heteroarenes
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Intermolecular C-H difluoromethoxylation of (hetero)arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a redox-active difluoromethoxylating reagent 1a and photoredox catalysts for the direct C-H difluoromethoxylation of (hetero)arenes. Our approach is operationally simple, proceeds at room temperature, and uses bench-stable reagents. Its synthetic utility is highlighted by mild reaction conditions that tolerate a wide variety of functional groups and biorelevant molecules. Experimental and computational studies suggest single electron transfer (SET) from excited photoredox catalysts to 1a forming a neutral radical intermediate that liberates the OCF2H radical exclusively. Addition of this radical to (hetero)arenes gives difluoromethoxylated cyclohexadienyl radicals that are oxidized and deprotonated to afford the products of difluoromethoxylation.
- Lee, Johnny W.,Zheng, Weijia,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
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p. 3217 - 3222
(2019/03/21)
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- Changes in the activity and selectivity of herbicides by selective fluorine substitution, taking bentranil and classic analogues as examples
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The introduction of fluorine atoms into 2-phenyl-4H-3,1-benzoxazin-4-one (bentranil) led to sweeping changes in its herbicidal properties in some cases, and 5-fluoro-2-phenyl-4H-3,1-benzoxazin-4-one ('fluorobentranil') was found to be the most active compound. It can be prepared from 2-amino-6-fluoro-benzoic acid or by direct halogen exchange of 5-chloro-2-phenyl-4H-3,1-benzoxazin-4-one. The latter reaction was investigated on a pilot scale, including a high-temperature (350°C) potassium fluoride halogen exchange without solvent. When sulfolane was used as a solvent, a side reaction at 220°C - partial decomposition to a diphenylether - could be prevented by addition of a small amount of a radical scavenger. Other intermediates with a pseudohalogen substitution were obtained by side-chain chlorination of suitable methylsulfanyl benzoic acid precursors and halogen exchange. 'Fluorobentranil' shows good broad-leaf activity and selectivity on rice, cereals and maize. In a second case study, the fluoro-substituted anthranilic acids mentioned above were also found to be appropriate for synthesizing herbicidal sulfonylurea (SU) compounds via Meerwein reaction of their aniline function. Methyl 2-[({[(4-chloro-6-methoxy-2- pyrimidinyl)-amino]carbonyl}amino)sulfonyl]-6-fluorobenzoate is an example of a SU that is compatible with maize, whereas the unsubstituted Classic analogue is not selective.
- Hamprecht, Gerhard,Wuerzer, Bruno,Witschel, Matthias
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p. 117 - 122
(2007/10/03)
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- Substituted 3-fluoroalkoxybenzoyl halides and their preparation
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Novel substituted 3-fluoroalkoxybenzoyl halides of the formula STR1 where Hal is fluorine or chlorine, R1 is chlorodifluoromethyl, difluoromethyl, 1,1,2,2-tetrafluoroethyl, 2-bromo-1,1,2-trifluoroethyl, pentafluoroethyl or 1,1,2,3,3,3-hexafluor
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- 4H-3,1-Benzoxazine derivatives
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4H-3,1-Benzoxazine derivatives of the formula STR1 where R1, R2 and Y have the meanings given in the specification, and their use for controlling unwanted plant growth in numerous crops, such as cereals, Indian corn, soybeans and cot
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