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.
Novel 5-methyltetrazolo[l,5-_a]quino~alin-4-0nes ( 5 ) and 5-methyl-1,2,4-triazolo[4,3-qlquinoxalin-4-ones ( I ) could be synthesized from 1-methyl-3-chloroquinoxalin-2-ones ( 3 ) and 1 -m e t h y l -3 -h y d r a z i n o q u i n o x a l i n -2 -o n e s (51, respectively. Further extensive study was carried out to synthesize 4or 7substituted and 4,7-disubstituted tetrazolo[l,5-~Iquinoxalines (g) and 1,2,4-triazolo[4,3-_a]quinoxalines (1_2). Recently, it has been reported that 4-methyltetrazolo[l,5-_~]quinazolin-5-one 1 2 (PP-389) and 5-methyl-1,2,4-triazolo[3,4-~]ben~othiazole (tricyclazole) have been excellent fungicides against P y r i c u l a r i a oryzae and inhibited the pathway of melanine biosynthesis.Figure 1.5 , intramolecular cyclizations of 9 to I_O were checked by their ir spectral data.When 2-chloro-6-fluoroquinox~1ine was allowed to react with sodium azide, a mixture of 7-fluorotetrazolo[l,5-alquinoxaline -(12b) and maybe ipso-substituted 7-azidotetrazolo[l,5-+]quinoxaline (1Ai) was obtained. The formation of 12i was assumed by the mass spectral data. On the other hand, the reactions of 8 with hydrazine hydrate furnished 2-hydrazinoquinoxalines (g), which were converted into 1 _ 2 bby
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