title: The cyclization transformation of the sulfonylurea herbicide flupyrsulfuron in the soil of winter wheat crops.
abstract: The synthesis of 1-(4,6-dimethoxypyrimidine-2-yl)-7-trifluoromethyl-1,2,3,4-tetrahydropyrido [2,3-d]pyrimidin-2,4-dione has been carried out in such a way that the dimethoxypyrimidine substituent was unambiguously in position 1 of the pyrido[2,3-d]pyrimidine ring. This regioisomer was obtained by cyclization with phosgene of 2-(4,6-dimethoxypyrimidin-2-ylamino)-6-trifluoromethylnicotinamide which had previously been ionized with sodium hydride. It was shown to be identical to the metabolite generated in the soil of winter wheat crops treated previously with the sulfonylurea herbicide flupyrsulfuronmethyl [(methyl 2-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-6-trifluoromethylnicotinate]. The position of the dimethoxypyrimidine substituent had not previously been assigned unambiguously to positions 1 or 3 of the pyrido[2,3-d]pyrimidine ring. The regioisomer was also identical to the cyclization compound generated chemically from flupyrsulfuron in a sterile water buffer at pH 9. The metabolism pathways of flupyrsulfuron in soil are discussed in the light these structure determinations and compared with the soil metabolism pathways frequently observed with other sulfonylurea herbicides.
authors.affiliation: Laboratory of Phytopharmacy, Université Catholique de Louvain, PO Box 6, 1348 Louvain-la-Neuve, Belgium. rouchaud@bgsh.ucl.ac.be
authors.forename: Jean
authors.initials: J
authors.lastname: Rouchaud
authors.forename: Olivier
authors.initials: O
authors.lastname: Neus
authors.forename: Claude
authors.initials: C
authors.lastname: Moulard
mesh_terms: D003500:Cyclization; D006540:Herbicides / Q000737:chemistry* / Q000378:metabolism; D007536:Isomerism; D015394:Molecular Structure; D011743:Pyrimidines / Q000737:chemistry* / Q000378:metabolism; D012987:Soil; D012989:Soil Pollutants / Q000378:metabolism; D013453:Sulfonylurea Compounds / Q000737:chemistry* / Q000378:metabolism; D014908:Triticum
chemical_list: D006540:Herbicides; D011743:Pyrimidines; D012987:Soil; D012989:Soil Pollutants; D013453:Sulfonylurea Compounds; C412905:flupyrsulfuron