Weiser Martin, Hermann Sergej, Penner Alexander, Wagenknecht Hans-Achim
Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
Beilstein J Org Chem. 2015 Apr 27;11:568-575. doi: 10.3762/bjoc.11.62. eCollection 2015.
The nucleophilic addition of methanol and other alcohols to 1,1-diphenylethylene () and styrene () into the Markovnikov- and anti-Markovnikov-type products was selectively achieved with 1-(,-dimethylamino)pyrene (Py) and 1,7-dicyanoperylene-3,4:9,10-tetracarboxylic acid bisimide (PDI) as photoredox catalysts. The regioselectivity was controlled by the photocatalyst. For the reductive mode towards the Markovnikov-type regioselectivity, Py was applied as photocatalyst and triethylamine as electron shuttle. This approach was also used for intramolecular additions. For the oxidative mode towards the anti-Markovnikov-type regioselectivety, PDI was applied together with Ph-SH as additive. Photocatalytic additions of a variety of alcohols gave the corresponding products in good to excellent yields. The proposed photocatalytic electron transfer mechanism was supported by detection of the PDI radical anion as key intermediate and by comparison of two intramolecular reactions with different electron density. Representative mesoflow reactor experiments allowed to significantly shorten the irradiation times and to use sunlight as "green" light source.
以1-(α,α-二甲基氨基)芘（Py）和1,7-二氰基苝-3,4:9,10-四羧酸双酰亚胺（PDI）作为光氧化还原催化剂，甲醇和其他醇类对1,1-二苯乙烯（ ）和苯乙烯（ ）的亲核加成反应能够选择性地生成马氏和反马氏类型的产物。区域选择性由光催化剂控制。对于生成马氏类型区域选择性的还原模式，使用Py作为光催化剂，三乙胺作为电子穿梭体。该方法也用于分子内加成反应。对于生成反马氏类型区域选择性的氧化模式，将PDI与Ph-SH作为添加剂一起使用。多种醇类的光催化加成反应能以良好至优异的产率得到相应产物。通过检测作为关键中间体的PDI自由基阴离子以及比较两个具有不同电子密度的分子内反应，支持了所提出的光催化电子转移机理。典型的微流反应器实验能够显著缩短照射时间，并使用阳光作为“绿色”光源。
