Zheng Guangfan, Li Yan, Han Jingjie, Xiong Tao, Zhang Qian
Department of Chemistry, Northeast Normal University, Changchun 130024, China.
Nat Commun. 2015 Apr 22;6:7011. doi: 10.1038/ncomms8011.
Cascade reactions initiated by radical addition to alkynes are synthetically very attractive because they enable access to highly complex molecular skeletons in only few synthetic steps under usually mild conditions. Here we report a general radical cascade reaction of alkynes, N-fluoroarylsulfonimides and alcohols, enabling the efficient synthesis of important α-amino-α-aryl ketones from readily available starting materials via a single operation. During this process, the highly regioselective nitrogen-centred radical addition to internal and terminal alkynes generating vinyl radicals and the next explicit migration of aryl group from the nitrogen source lead the following efficient desulfonylation, oxygenation, and semi-pinacol rearrangement. In addition, the semi-pinacol rearrangement precursors, α-alkyloxyl-α,α-diaryl imines, could also be efficiently obtained under milder conditions. This methodology might open a new entry for designing intermolecular radical cascade reaction of alkynes.
通过向炔烃加成自由基引发的级联反应在合成方面极具吸引力，因为它们能够在通常温和的条件下仅通过几步合成操作就获得高度复杂的分子骨架。在此，我们报道了一种炔烃、N-氟芳基磺酰亚胺和醇的通用自由基级联反应，该反应能够通过单一操作从易得的起始原料高效合成重要的α-氨基-α-芳基酮。在此过程中，高度区域选择性的以氮为中心的自由基加成到内炔和端炔上生成乙烯基自由基，随后芳基从氮源发生明确的迁移，进而引发高效的脱磺酰化、氧化和半频哪醇重排。此外，在更温和的条件下也能够高效获得半频哪醇重排前体α-烷氧基-α,α-二芳基胺。该方法可能为设计炔烃的分子间自由基级联反应开辟一条新途径。
