4837-19-8Relevant academic research and scientific papers
DIFLUOROMETHOXYLATION AND TRIFLUOROMETHOXYLATION COMPOSITIONS AND METHODS FOR SYNTHESIZING SAME
-
Page/Page column 75; 79; 89; 102-103, (2019/09/18)
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.
Catalytic radical difluoromethoxylation of arenes and heteroarenes
Lee, Johnny W.,Zheng, Weijia,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
, p. 3217 - 3222 (2019/03/21)
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.
Changes in the activity and selectivity of herbicides by selective fluorine substitution, taking bentranil and classic analogues as examples
Hamprecht, Gerhard,Wuerzer, Bruno,Witschel, Matthias
, p. 117 - 122 (2007/10/03)
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.
Substituted 3-fluoroalkoxybenzoyl halides and their preparation
-
, (2008/06/13)
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
4H-3,1-Benzoxazine derivatives
-
, (2008/06/13)
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
