Halogenation of N-oxygenated pyrazoles. Preparation of N-oxygenated 4-halopyrazole and 4, 4-dihalo-4H-pyrazole derivatives

…, LJ Griswold, GW Hoelle, DL Taylor…

Index: Hansen, John F.; Kim, Yong In; Griswold, Linus J.; Hoelle, Gary W.; Taylor, Deborah L.; Vietti, David E. Journal of Organic Chemistry, 1980 , vol. 45, # 1 p. 76 - 80

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Citation Number: 19

Abstract

Results Solutions of the I-hydroxypyrazole 2-oxides (1) in aqueous ethanolic potassium carbonate reacted rapidly with 1 molar equiv of iodine-potassium iodide at room temperature, and the 4-iodo-1-hydroxypyrazole 2-oxides (3, X= I) precipitated upon acidification. Halogenation using N-chlorosuccinimide (NCS) or N-bromosuccinimide (NBS) under similar conditions gave the corresponding 3 (X= C1 or Br). The 1-hydroxypyrazoles ...