Electron-Transfer Photoredox Catalysis: Development of a Tin-Free Reductive Dehalogenatioin Reaction
Electron-Transfer Photoredox Catalysis: Development of a Tin-Free Reductive Dehalogenatioin Reaction
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DOI：
10.1021/ja9033582
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发表时间：
2009-07-01
影响因子：
15
通讯作者：
Stephenson, Corey R. J.
中科院分区：
文献类型：
--
作者：
Narayanam, Jagan M. R.;Tucker, Joseph W.;Stephenson, Corey R. J.
我们报道了一种操作简单、无锡的还原脱卤系统，该系统利用著名的可见光激活光氧化还原催化剂Ru(bpy)(3)Cl-2与'Pr2NEt和HCO2H或Hantzsch酯作为氢原子供体相结合。活化的 C-X 键可以以良好的产率还原，并且相对于芳基和乙烯基 C-X 键具有优异的官能团耐受性和化学选择性。所提出的机制涉及催化剂的可见光激发，催化剂被 3 度胺还原生成单电子还原剂 Ru(bpy)(3)(+)。随后的单电子转移产生烷基自由基，该烷基自由基通过夺取氢原子而猝灭。只需 0.05 mol% Ru 催化剂即可以制备规模实现还原。
We report an operationally simple, tin-free reductive dehalogenation system utilizing the well-known visible-light-activated photoredox catalyst Ru(bpy)(3)Cl-2 in combination with 'Pr2NEt and HCO2H or Hantzsch ester as the hydrogen atom donor. Activated C-X bonds may be reduced in good yields with excellent functional-group tolerance and chemoselectivity over aryl and vinyl C-X bonds. The proposed mechanism involves visible-light excitation of the catalyst, which is reduced by the 3 degrees amine to produce the single-electron reducing agent Ru(bpy)(3)(+). A subsequent single-electron transfer generates the alkyl radical, which is quenched by abstraction of a hydrogen atom. Reductions can be accomplished on a preparative scale with as little as 0.05 mol % Ru catalyst.