Efficient di-bromination of 5-pyrazolones and 5-hydroxypyrazoles by N-bromobenzamide

…, WN Su, KC Sung, TP Lin, JJ Huang, SK Lin, FF Wong

Index: Huang, Yu-Ying; Lin, Hui-Chang; Cheng, Kaung-Min; Su, Wei-Nien; Sung, Kuan-Chin; Lin, Tsung-Ping; Huang, Jiann-Jyh; Lin, Shao-Kai; Wong, Fung Fuh Tetrahedron, 2009 , vol. 65, # 46 p. 9592 - 9597

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Citation Number: 24

Abstract

Traditional methods for the synthesis of brominated pyrazolones contain the use of Br 2 in acetic acid, 12, 12a and 12b however, the harsher conditions require manipulations with care. Ahmed et al. have treated the pyrazolones with N-bromosuccinimide (NBS) to perform the photochemical bromination. 16 Since the reaction also provided the mono-substituted and coupling by-products, the desired dibromopyrazolines were obtained in low yields. 16 ...