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Molecules 2009, 14(2), 777-784; doi:10.3390/molecules14020777
Article

Methyl Carbonium Ion Migration during the Reaction of 4-Chloro-5-methoxyl-3(2H)-pyridazinone with Trifluoroethylation Agents

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, , *  and
The State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Xue Yuan Road #38, Beijing 100191, P.R. China
* Author to whom correspondence should be addressed.
Received: 20 November 2008 / Revised: 18 December 2008 / Accepted: 4 January 2009 / Published: 13 February 2009
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Abstract

To synthesize 4-chloro-5-methoxy-2-(b-trifluoroethyl)-3(2H)-pyridazinone (4), the reactions of 4-chloro-5-methoxy-3(2H)-pyridazinone (5) with RCH2CF3 (R = I, TsO, MsO, TfO) in different solvents were studied. It was found that methyl group migration took place during this reaction. An oxonium salt 9 was suggested as the active intermediate for the formation of the byproduct4-chloro-5-methoxy-2-methyl-3(2H)-pyridazinone (7) and 4-chloro-2-methyl-5-(b-trifluoroethoxy)-3(2)-pyridazinone(8).
Keywords: 4; 5-Dichloro-3(2H)-pyridazinone; 4-Chloro-5-methoxy-3(2H)-pyridazinone; -Trifluoroethylation; Oxonium; Methyl group migration; Alkylation 4; 5-Dichloro-3(2H)-pyridazinone; 4-Chloro-5-methoxy-3(2H)-pyridazinone; -Trifluoroethylation; Oxonium; Methyl group migration; Alkylation
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Li, Q.; Lin, G.; Liu, L.; Yang, Z.; Zhang, L.-H. Methyl Carbonium Ion Migration during the Reaction of 4-Chloro-5-methoxyl-3(2H)-pyridazinone with Trifluoroethylation Agents. Molecules 2009, 14, 777-784.

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