Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States.
J Am Chem Soc. 2021 Nov 3;143(43):18331-18338. doi: 10.1021/jacs.1c09484. Epub 2021 Oct 21.
New strategies to access radicals from common feedstock chemicals hold the potential to broadly impact synthetic chemistry. We report a dual phosphine and photoredox catalytic system that enables direct formation of sulfonamidyl radicals from primary sulfonamides. Mechanistic investigations support that the N-centered radical is generated via α-scission of the P-N bond of a phosphoranyl radical intermediate, formed by sulfonamide nucleophilic addition to a phosphine radical cation. As compared to the recently well-explored β-scission chemistry of phosphoranyl radicals, this strategy is applicable to activation of N-based nucleophiles and is catalytic in phosphine. We highlight application of this activation strategy to an intermolecular anti-Markovnikov hydroamination of unactivated olefins with primary sulfonamides. A range of structurally diverse secondary sulfonamides can be prepared in good to excellent yields under mild conditions.
从常见原料化学品中获取自由基的新策略有可能广泛影响合成化学。我们报告了一种双膦和光氧化还原催化体系，能够从伯磺酰胺直接形成磺酰胺基自由基。机理研究支持 N-中心自由基是通过磷自由基阳离子加成到膦自由基中间体的 P-N 键的α断裂形成的。与最近广泛探索的磷自由基的β断裂化学相比，该策略适用于 N 基亲核试剂的活化，并且在膦中具有催化作用。我们强调了这种活化策略在与伯磺酰胺的未活化烯烃的反 Markovnikov 氢胺化中的应用。在温和条件下，可以以良好至优异的收率制备一系列结构多样的仲磺酰胺。
