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Synthesis 2005(7): 1136-1140  
DOI: 10.1055/s-2005-861845
PAPER
© Georg Thieme Verlag Stuttgart · New York

2-Chloropyridazin-3(2H)-ones as Electrophilic Chlorinating Agents: Effective α-Chlorination of Active Methylene/Methine Compounds

Yong-Dae Parka, Jeum-Jong Kima, Su-Dong Chob, Sang-Gyeong Leec, J. Russell Falckd, Yong-Jin Yoon*a
a Department of Chemistry & Research Institute of Natural Sciences, Gyeongsang National University, Chinju 660-701, Korea
Fax: +82(55)7610244; e-Mail: yjyoon@nongae.gsnu.ac.kr;
b Department of Chemistry & Research Institute of Basic Scienc, Changwon National University, Changwon 641-773, Korea
c Department of Chemistry & Research Institute of Life Science, Gyeongsang National University, Chinju 660-701, Korea
d Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Publication History

Received 27 October 2004
Publication Date:
09 March 2005 (online)

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Abstract

2,4,5-Trichloro- (2a) and 2,4-dichloro-5-methoxypyridazin-3(2H)-one (2b) are novel electrophilic chlorinating agents. α-Chlorination of active methylene/methine compounds with 2 in the presence of either Lewis or protonic acids in dichloromethane (for Lewis acid) or water (for protonic acid or none) at room temperature gave also selectively α-monochlorides and/or α,α-dichlorides in good to excellent yields.

Key words

α-chlorination - 2,4,5-trichloropyridazin-3(2H)-one - electrophilic chlorination - electrophilic chlorinating agent