Synthesis of fluoromethyl, difluoromethyl and trifluoromethyl analogues of pyrazosulfuron‐ethyl as herbicides

Abstract

Ethyl 1‐fluoromethyl‐5‐(4,6‐dimethoxypyrimidin‐2‐ylcarbamoylsulfamoyl)pyrazole‐4‐carboxylate 1b, a new fluoromethyl analogue of the herbicide pyrazosulfuron‐ethyl la, was prepared from ethyl 1‐fluoromethylpyrazole‐4‐carboxylate 4b. The difluoromethyl and trifluoromethyl analogues 1c,d were also synthesized from ethyl pyrazole‐4‐carboxylate 2 via difluorocarbene reaction.

Synthesis of New 1,2,4-Triazole[3,4-b][1,3,4]thiadiazoles Bearing Pyrazole as Potent Antimicrobial Agents

“…Similarly, the absence of signals for the -SH and -NH 2 protons in the 1 H-NMR spectra followed by the presence of aromatic protons in the region of d 7.60 and 7.92 ppm well support the structures. In the 13 C-NMR spectra, the prominent signals corresponding to the carbons of [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazole ring for all the compounds, observed nearly at d 152.1, 144.3 and 134.9 ppm are proof of further evidence of their structures. In summary all the newly synthesized compounds exhibited satisfactory spectral data consistent with their molecular structures.…”

“…Reaction of 5 with hydrazine hydrate under reflux for 6 h resulted 4-amino-5-(5-methyl-1-phenyl-1H-4-pyrazolyl)-4H-1,2,4-triazol-3-yl-hydrosulfide (6) in 69% yield. The final compounds, 6-(aryl/heteryl)-3-(5-methyl-1-phenyl-1H-4-pyrazolyl) [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazole (7a-j), were synthesized in 66-78% via the reaction of 6 with POCl 3 and the corresponding aryl/heteryl carboxylic acids, in ethanol at reflux temperature for 12 h (Chart 1). The structures of all the newly synthesized compounds were confirmed by their elemental analyses, electron ionization (EI) mass, IR, 1 H-and 13 C-NMR spectral data.…”

“…Inspired by the biological profile of pyrazole, triazole, thiadiazole, and in continuation of our research on biologically active heterocycles, [30][31][32][33][34][35] it was thought worthwhile to synthesize some new heterocyclic compounds containing pyrazole, triazole and thiadiazol rings in one molecular frame work. We report herein the synthesis of a new series of 1,2,4-triazole [3,4-b] [1,3,4]thiadiazoles bearing pyrazole and their antimicrobial activity.…”

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Pyrazole and its derivatives represent one of the most active classes of compounds possessing a wide spectrum of biological activities, including antibacterial, 1) antifungal, 2) herbicidal, 3) insecticidal 4) and other biological activities.

5-7)Similarly, the biological activities of various 1,2,4-triazole derivatives and their N-bridged heterocyclic analogs have been widely investigated as antitumor, 8) antiviral, 9) anti-inflammatory, 10) analgesic 11) and antidepressant. 12) 1,2,4-Triazole system is also an important starting material in the synthesis of biologically active heterocycles, which constitute an important class of organic compounds with diverse biological activities, including antiparasitic, analgesic, antibacterial and anti-inflammatory activities.

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“…Pyrazole and its derivatives represent one of the most active classes of compounds possessing a wide spectrum of biological activities, including antibacterial, 1) antifungal, 2) herbicidal, 3) insecticidal 4) and other biological activities.…”