Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
J Am Chem Soc. 2020 Apr 1;142(13):5974-5979. doi: 10.1021/jacs.0c01332. Epub 2020 Mar 20.
An enantioselective, radical-based method for the intramolecular hydroamination of alkenes with sulfonamides is reported. These reactions are proposed to proceed -centered radicals formed by proton-coupled electron transfer (PCET) activation of sulfonamide N-H bonds. Noncovalent interactions between the neutral sulfonamidyl radical and a chiral phosphoric acid generated in the PCET event are hypothesized to serve as the basis for asymmetric induction in a subsequent C-N bond forming step, achieving selectivities of up to 98:2 er. These results offer further support for the ability of noncovalent interactions to enforce stereoselectivity in reactions of transient and highly reactive open-shell intermediates.
本文报道了一种对映选择性、基于自由基的方法，用于亚砜与烯烃的分子内氢胺化反应。这些反应被认为是通过质子耦合电子转移 (PCET) 激活亚砜 N-H 键形成中心自由基。假设在 PCET 事件中生成的中性亚磺酰基自由基与手性磷酸之间的非共价相互作用是后续 C-N 键形成步骤中不对称诱导的基础，实现了高达 98:2 的对映选择性。这些结果进一步支持了非共价相互作用在瞬态和高反应性开壳中间体反应中强制立体选择性的能力。
