Xichang Dong, Youwei Xu, J. Liu
Dec 9, 2013
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Influential Citations
47
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Chemistry
Abstract
351591 (Scheme 1, II) has been identified as a potent and highly selective type 4 phosphodiesterase (PDE4) inhibitor. Quinoline-based compound III (Scheme 1), target DNA topoisomerase IV, and DNA gyrase, can be used as antituberculosis agents. As a consequence, the development of an efficient method for the synthesis of 2-trifluoromethyl quinoline derivatives has become a subject of great interest. Among the methods to construct such structures, transition-metal-catalyzed reactions of trifluoroacetimidoyl halides with alkynes have been studied extensively in recent years. For example, Uneyama et al. reported a one-pot synthesis of 2-trifluoromethyl quinolines by Rh-catalyzed cyclization of N-aryl trifluoroacetimidoyl chlorides with alkynes. Wu and co-workers developed a Cu-catalyzed coupling reaction and subsequent cyclization to construct 4-substituted 2-fluoromethylated quinolines. These reported reactions employ easily available trifluoroacetimidoyl halides as the starting materials, albeit with poor regioselectivity in some cases. Compared to transition-metal-catalyzed reactions, the radical pathway involving intermolecular addition of trifluoroACHTUNGTRENNUNGacetimidoyl radical to alkynes and subsequent annulation has received less attentions. Generation of trifluoroacetimidoyl radical has been examined by three different pathways, including: 1) tin-radical-mediated deiodination of imidoyl iodides (Scheme 2a); 2) homolytic cleavage of the