Markovnikov-Selective Radical Addition of S-Nucleophiles to Terminal Alkynes through a Photoredox Process
作者:Huamin Wang、Qingquan Lu、Chien-Wei Chiang、Yi Luo、Jiufu Zhou、Guangyu Wang、Aiwen Lei
DOI:10.1002/anie.201610000
日期:2017.1.9
Direct radical additions to terminal alkynes have been widely employed in organic synthesis, providing credible access to the anti‐Markovnikov products. Because of the Kharasch effect, regioselective control for the formation of Markovnikov products still remains a great challenge. Herein, we develop a transition‐metal‐free, visible light‐mediated radical addition of S‐nucleophiles to terminal alkynes
末端炔烃中的直接自由基加成已被广泛用于有机合成中,从而提供了可靠的反马尔科夫尼科夫产品的途径。由于Kharasch效应,用于马尔可夫尼可夫产物形成的区域选择性控制仍然是巨大的挑战。本文中,我们开发了无过渡金属,可见光介导的S-亲核基团向末端炔烃的自由基加成反应,从而提供了多种具有独家Markovnikov区域选择性的α-取代乙烯基砜。机理研究表明,自由基/自由基的交叉偶联可能是这一转变的关键步骤。这种自由基的马尔可夫尼科夫加成方案也为促进其他有价值的α-取代的乙烯基化合物的合成提供了机会。