Regioselective Iron-Catalyzed [2 + 2 + 2] Cycloaddition Reaction Forming 4,6-Disubstituted 2-Aminopyridines from Terminal Alkynes and Cyanamides

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• 作者：Nathan A. Spahn ; Minh H. Nguyen ; Jonas Renner ; Timothy K. Lane ; Janis Louie
• 刊名：Journal of Organic Chemistry
• 出版年：2017
• 出版时间：January 6, 2017
• 年：2017
• 卷：82
• 期：1
• 页码：234-242
• 全文大小：587K
• ISSN：1520-6904

文摘

Iron complexes bound by redox-active pyridine dialdimine (PDAI) ligands catalyze the cycloaddition of two terminal alkynes and one cyanamide. The reaction is both chemo- and regioselective, as only 4,6-disubstituted 2-aminopyridine products are formed in moderate to high yields. Isolation of an iron azametallacycle (4) suggests that catalyst deactivation occurs with a large excess of cyanamide over longer reaction times. Fe-catalyzed cycloaddition allowed for a straightforward synthesis of a variety of aminopyridines, including known estrogen receptor ligands.