- Selective fluorination of an aryl triazolinone herbicide intermediate
-
Fluoroaryl 1,2,4-triazolin-5-ones are an important class of herbicidal compounds useful in a variety of crop protection applications, primarily for the control of grassy and broad-leaf plant species. While a number of different synthetic strategies can be used for the step-wise preparation of these complex molecules, it is generally preferred to introduce fluorine later in the synthetic pathway, since the presence of fluorine and other halogens has a dominant effect on all subsequent synthetic steps. We have investigated the reactions that occur between aryl triazolinones and a variety of fluorination agents, including F2/N2, XeF2, (CF3SO2)2NF, Selectfluor, CF2(OF)2, CF3OF, CH3COOF, and CF3COOF, and have used this knowledge to develop several alternative high-yielding routes to fluoroaryl 1,2,4-triazolin-5-ones. The fluorine introduction strategy and experimental results for a representative example of this important class of compounds are discussed herein.
- Syvret, Robert G.,Casteel Jr., William J.,Lal, G. Sankar,Goudar, Jaidev S.
-
-
Read Online
- Synthesis method of intermediate [...][...] and
-
The invention discloses a method for synthesizing carfentrazone-ethyl and a carfentrazone-ethyl intermediate. The method comprises the following steps: taking 1-(4-chloro-2-fluorophenyl)-3-methyl-1H-1,2,4-triazole-5-ketone as a raw material; carrying out difluoridate methylation, nitrification, catalytic hydrogenation reduction and diazo arylation to obtain 2-chloro-3-{2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxygen-1H-1,2,4-triazole-1-radical]-4-fluorophenyl}propionic acid or carfentrazone-ethyl final product. The method disclosed by the invention has the benefits of simplified integral process, mild reaction conditions, high yield, and high quality of products, thereby facilitating industrial production.
- -
-
Paragraph 0040; 0042
(2017/04/06)
-
- Continuous preparation of high purity Bis(fluoroxy)difluoromethane (BDM) at elevated pressure
-
The invention provides an improved process for preparing bis(fluoroxy)difluoro-methane (BDM) by continuously reacting F2 with CO2 in a reactor containing a fluorination catalyst (e.g., CsF), wherein the process is conducted at a pressure above atmospheric pressure. The process provides BDM of very high purity and very low residual F2.
- -
-
-
- Regioselective fluorination of phenyl-substituted triazolinones
-
A process for the preparation of a compound of the Formula I wherein the process comprising the step of treating a compound of the Formula II with a fluorinating agent at a temperature of about 60° to about 120° C. in the presence of an organic solvent to form a compound of the Formula I; wherein: X, R or R′ can optionally be independently protected with a protecting group which is substantially stable to the fluorinating agent; and where X, R, and R′ are described herein.
- -
-
-
- Process for the preparation of a triazolinone herbicide
-
A process for preparing an alkyl alpha -2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-2,4-substituted-benzene-propanoate herbicide, by reacting an alkyl alpha -acetyl-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-2,4-disubstituted-benzene-propanoate, Intermediate D, first with sodium hypochlorite, then with a base, and recovering the herbicide. Intermediate D is prepared by reacting a 1-(2, 4-disubstituted-5-halophenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazole, Intermediate B, with an alkyl alkanoate in the presence of a palladium catalyst and a tertiary amine. Intermediate B is prepared by reacting a 1-(2,4-disubstituted-phenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazole with a halogenating agent in the presence of an acid. The 2,4-substituents are independently selected from halo, alkyl, cycloalkyl, alkoxy, nitro, or hetercyclyl.
- -
-
-