Chlorine Atom Transfer of Unactivated Alkyl Chlorides Enabled by Zirconocene and Photoredox Catalysis
Chlorine Atom Transfer of Unactivated Alkyl Chlorides Enabled by Zirconocene and Photoredox Catalysis
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DOI：
10.1021/prechem.2c00002
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发表时间：
2023-02
期刊：
影响因子：
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通讯作者：
Toshimasa Okita;Kazuhiro Aida;Keisuke Tanaka;Eisuke Ota;Junichiro Yamaguchi
中科院分区：
文献类型：
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作者：
Toshimasa Okita;Kazuhiro Aida;Keisuke Tanaka;Eisuke Ota;Junichiro Yamaguchi
烷基氯是碳自由基的稳定前体;然而，它们的相对惰性阻碍了它们的实际应用。虽然现代光化学策略大大提高了烷基氯作为自由基前体的效用，但这些方法通常依赖于导致非生产性副反应的强烈还原条件。在这里，我们报告了从1°，2°和3°未活化的烷基氯化物与二茂锆和光氧化还原催化的催化自由基生成，这使得在一系列结构复杂的分子上进行氢化和硼基化。这种温和的二茂锆催化的方案表明，锆可以使C-Cl键断裂更多的放能，并可以降低过渡态的活化能，放大了二茂锆向卤素原子转移的能力。
Alkyl chlorides are robust precursors to carbon radicals; however, their relative inertness has hampered their practical use. Although modern photochemical strategies have greatly enhanced the utility of alkyl chlorides as radical precursors, these methods often depend on strongly reducing conditions leading to unproductive side reactions. Here, we report a catalytic radical generation from 1°, 2°, and 3° unactivated alkyl chlorides with zirconocene and photoredox catalysis, which enables both hydrogenation and borylation on a range of structurally complex molecules. This mild zirconocene-catalyzed protocol shows that zirconium can render the C–Cl bond cleavage more exergonic and can lower the activation energy of the transition state, amplifying the ability of metallocenes toward halogen atom transfer.