C(
<i>sp</i>
<sup>3</sup>
)−C(
<i>sp</i>
<sup>3</sup>
) Cross‐Coupling of Alkyl Bromides and Ethers Mediated by Metal and Visible Light Photoredox Catalysis
作者:Marilia S. Santos、Arlene G. Corrêa、Márcio W. Paixão、Burkhard König
DOI:10.1002/adsc.202000167
日期:2020.6.15
We report a C(sp 3)−C(sp 3) cross‐coupling of alkyl bromides and alkyl chlorides with ethers by dual photoredox‐nickel catalysis. The catalytic system comprises of the organic photocatalyst 1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene (4‐CzIPN) and bench stable nickel (II) acetylacetonate in the presence of visible‐light, providing the coupling products in up to 92% yield. Preliminary mechanistic
我们报道了通过双光氧化还原镍催化的烷基溴和烷基氯与醚的C(sp 3)-C(sp 3)交叉偶联。催化体系由可见光下的有机光催化剂1,2,3,5-四(咔唑-9-基)-4,6-二氰基苯(4-CzIPN)和稳定的乙酰丙酮镍(II)组成,以高达92%的产率提供耦合产品。初步的机理研究表明,存在两个催化循环,以及偶合伙伴结构中存在的卤原子产生溴或氯自由基的光生化。卤化物自由基介导氢原子转移事件,从而避免了额外的HAT催化剂的需要。