Flazasulfuron

Flazasulfuron
Names
Preferred IUPAC name
N-[(4,6-Dimethoxypyrimidin-2-yl)carbamoyl]-3-(trifluoromethyl)pyridine-2-sulfonamide
Other names
Katana, Shibagen
Identifiers
CAS Number
  • 104040-78-0 checkY
3D model (JSmol)
  • Interactive image
ChemSpider
  • 84440
ECHA InfoCard 100.123.655 Edit this at Wikidata
PubChem CID
  • 93539
UNII
  • 3SB13WWV30 checkY
CompTox Dashboard (EPA)
  • DTXSID3034610 Edit this at Wikidata
InChI
  • InChI=1S/C13H12F3N5O5S/c1-25-8-6-9(26-2)19-11(18-8)20-12(22)21-27(23,24)10-7(13(14,15)16)4-3-5-17-10/h3-6H,1-2H3,(H2,18,19,20,21,22)
    Key: HWATZEJQIXKWQS-UHFFFAOYSA-N
  • InChI=1/C13H12F3N5O5S/c1-25-8-6-9(26-2)19-11(18-8)20-12(22)21-27(23,24)10-7(13(14,15)16)4-3-5-17-10/h3-6H,1-2H3,(H2,18,19,20,21,22)
    Key: HWATZEJQIXKWQS-UHFFFAOYAQ
  • COc1cc(nc(n1)NC(=O)NS(=O)(=O)c2c(cccn2)C(F)(F)F)OC
Properties
Chemical formula
 C13H12F3N5O5S
Molar mass 407.3
Appearance white solid
Melting point 166-170
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
Chemical compound

Flazasulfuron is a sulfonylurea herbicide used for controlling the unwanted growth of grass, broad-leaved weeds and sedges. The mode of action of flazasulfuron is through the inhibition of the enzyme acetolactate synthase (ALS), which results in the inhibition of amino acid synthesis, cell division and ultimately plant growth. Flazasulfuron can be used on both pre-emergent weeds and post-emergent weeds. Growth ceases within hours of the application of the compound. Symptoms include leaf discolouration, desiccation, necrosis and ultimately plant death within 20 – 25 days of application. It is a white, water-soluble solid.[1]

Synthesis

The synthesis of flazasulfuron begins with the one pot chlorination and chlorine/fluorine exchange of 3-picoline[2] (1). This reaction is performed in the gas phase in a purpose built reactor where the desired product (2) is one of the components of the crude product mixture.[3] Treatment of (2) with sodium hydrosulfide gives (3) by nucleophillic aromatic substitution. Acidic oxidation with chlorine produces the sulfonylchloride which is filtered off and added directly to chilled concentrated ammonia solution to produce 3-trifluoromethylpyridin-2-yl sulfonamide (4). Treatment with diphenylcarbonate (5) and sodium hydride gives the carbamate (6)[4]. Finally, flazasulfuron is obtained by the reaction of (6) with 4,6-dimethoxy-1-aminopyrimidine in dioxane.

An alternative strategy is to use (4) as nucleophile with the O-phenylcarbamate of 4,6-dimethoxy-1-aminopyrimidine (7) as electrophile in the presence of DBN.

References

  1. ^ Appleby, Arnold P.; Müller, Franz; Carpy, Serge (2001). "Weed Control". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a28_165. ISBN 978-3-527-30673-2.
  2. ^ Unger, Thomas A. (1996). "Flazasulfuron". Pesticide Synthesis Handbook. pp. 180–182. doi:10.1016/B978-081551401-5.50148-9. ISBN 978-0-8155-1401-5.
  3. ^ Tsukamoto, Masamitsu; Nakamura, Tadashi; Kimura, Hirohiko; Nakayama, Hitoshi (20 May 2021). "Synthesis and application of trifluoromethylpyridines as a key structural motif in active agrochemical and pharmaceutical ingredients". Journal of Pesticide Science. 46 (2): 125–142. doi:10.1584/jpestics.D21-012. PMC 8175224. PMID 34135675.
  4. ^ EP 0184385B1, Fumio Kimura et al., "N-[(4,6-Dimethoxypyrimidin-2-YL)Aminocarbonyl]-3-trifluoromethylpyridine-2-sulfonamide or salts thereof, herbicidal composition containing the same, and processs for the production of the compound", published 1986 
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