Herein we report the use of manganese(II) chloride for the catalytic generation of C(sp2)–C(sp3) bonds via Kumada cross-coupling. Rapid and selective formation of 2-alkylated N-heterocyclic complexes were observed in high yields with use of 3 mol% MnCl2THF1.6 and under ambient reaction conditions (21 °C, 15 min to 20 h). Manganese-catalyzed cross-coupling is tolerant toward both electron-donating and electron-withdrawing functional groups in the 5-position of the pyridine ring, with the latter resulting in an increased reaction rate and a decrease in the amount of nucleophile required. The use of this biologically and environmentally benign metal salt as a catalyst for C–C bond formation highlights its potential as a catalyst for the late-stage functionalization of pharmaceutically active N-heterocyclic molecules (e.g., pyridine, pyrazine).

中文翻译：

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锰催化的脂肪族格氏试剂与 N-杂环氯化物的 Kumada 交叉偶联反应

在此，我们报告了使用氯化锰 (II) 通过 Kumada 交叉偶联催化生成 C(sp2)–C(sp3) 键。在使用 3 mol% MnCl2THF1.6 和环境反应条件（21 °C，15 分钟至 20 小时）下，观察到 2-烷基化 N-杂环配合物的快速和选择性形成。锰催化的交叉偶联对吡啶环 5 位的给电子和吸电子官能团都具有耐受性，后者导致反应速率增加和所需亲核试剂的量减少。使用这种对生物和环境无害的金属盐作为 C-C 键形成的催化剂，突出了其作为药学活性 N-杂环分子（例如吡啶、吡嗪）后期功能化催化剂的潜力。