Abstract：
Dichloromethane, as a readily available and inexpensive C1 synthon is proposed as a powerful building block for cyclopropanation of alkenes under mild conditions. Herein, we report a highly efficient and versatile dual photoredox system, involving a nickel aminopyridine coordination complex and a photocatalyst, for the cyclopropanation of aromatic olefins using dichloromethane, under visible-light irradiation. The cyclopropanation protocol has been successfully applied at gram scale. Mechanistic studies suggest a Ni(II) pyridyl radical complex as the key intermediate for the homolytic cleavage of the Csp3-Cl bond, generating a chloromethyl radical that is captured by the olefin coupling partner. Our findings also highlight the versatility of this methodology. By directing the radical/polar crossover process, we were able to selectively drive the reaction towards either the formation of cyclopropyl derivatives or the corresponding non-cyclic alkyl chloride products. The methodology also successfully apply to geminal dichloroalkanes, including the formation of spiro[2,2] compounds. Moreover, our methodology extends to the synthesis of deuterium-labelled cyclopropanes, demonstrating its utility in isotopic labelling and broadening its applicability in chemical synthesis and drug development.
摘要：
二氯甲烷,作为一种容易获得且廉价的C1合成子，被建议作为在温和条件下进行烯烃环丙烷化的强大构建块。在这里，我们报告了一个高效和多功能的双光氧化还原系统，涉及镍氨基吡啶配位络合物和光催化剂，对于使用二氯甲烷的芳香族烯烃的环丙烷化，在可见光照射下。环丙烷化方案已成功应用于克规模。机理研究表明，Ni（II）吡啶基自由基络合物是Csp3-Cl键均裂的关键中间体，产生被烯烃偶联配偶体捕获的氯甲基自由基。我们的发现也强调了这种方法的多功能性。通过指导自由基/极性交叉过程，我们能够选择性地推动反应形成环丙基衍生物或相应的非环状烷基氯产物。该方法也成功地应用于双联二氯烷烃，包括螺[2,2]化合物的形成。此外，我们的方法扩展到氘标记的环丙烷的合成，证明其在同位素标记中的实用性，并扩大其在化学合成和药物开发中的适用性。
