Synthesis of halosulfuron??methyl via selective chlorination at 3??and/or 5??position of pyrazole??4??carboxylates

K Morimoto, T Sato, S Yamamoto…

文献索引：Morimoto, Katsushi; Sato, Toshiaki; Yamamoto, Susumu; Takeuchi, Hiroshi Journal of Heterocyclic Chemistry, 1997 , vol. 34, # 2 p. 537 - 540

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被引用次数: 15

摘要

Abstract Reactions of methyl pyrazole-4-carboxylates 4b-d with N-chlorosuccinimide under heating conditions without a solvent gave methyl 3, 5-dichloro-1-methylpyrazole-4- carboxylate 4a in good yields. The reaction of 4a with sodium hydrosulfide led to a nucleophilic substitution on the 5-position regioselectively to afford methyl 3-chloro-1-methyl- 5-mercaptopyrazole-4-carboxylate 6a, which was followed by oxidative chlorination and ...