Trifluoromethylative Bifunctionalization of Alkenes via a Bibenzothiazole-Derived Photocatalyst under Both Visible- and Near-Infrared-Light Irradiation
Trifluoromethylative Bifunctionalization of Alkenes via a Bibenzothiazole-Derived Photocatalyst under Both Visible- and Near-Infrared-Light Irradiation
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DOI：
10.1021/acscatal.3c01812
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发表时间：
2023-06
期刊：
影响因子：
12.9
通讯作者：
Bidyut Kumar Kundu;Chuan-qiang Han;Prasenjit Srivastava;Siddhant Nagar;Katie E. White;J. Krause;C. Elles;Yujie Sun
中科院分区：
文献类型：
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作者：
Bidyut Kumar Kundu;Chuan-qiang Han;Prasenjit Srivastava;Siddhant Nagar;Katie E. White;J. Krause;C. Elles;Yujie Sun
将三氟甲基引入农用化学品和药物等有机分子中引起了人们的极大兴趣，因为它们会影响所得分子的结合能力、亲脂性、代谢稳定性和化学稳定性。在过去的几年中，芳基烯烃的光催化三氟甲基化已有报道，这通常需要珍贵的含 Ru/Ir 光催化系统。在此，我们报道了一种由联苯并噻唑核和两个亚胺桥接的甲氧基苯基取代基（dBIP-OMe）组成的无金属有机光催化剂，它能够在不使用任何牺牲试剂的情况下光催化驱动烯烃的三氟甲基化双官能化。机理研究揭示了激发的 dBIP-OMe*、CF3 前体（Umemoto 试剂）和烯烃底物之间的两个连续的单电子转移步骤。底物范围研究表明，我们使用 dBIP-OMei 的三氟甲基化双官能化策略适用于芳基和脂肪族烯烃。此外，一旦完成最重要的三氟甲基化步骤，各种亲核试剂，如H2O、乙酸盐、氰化物、叠氮化物等，就可以很容易地掺入到碳正离子中间体中，从而大大拓宽了该光催化方法的应用范围。最后，利用dBIP-OMe在近红外区域的双光子吸收能力，我们证明了使用廉价的740 nm LED作为唯一光源可以实现苯乙烯的羟基三氟甲基化。
The incorporation of trifluoromethyl groups into organic molecules such as agrochemicals and pharmaceuticals has attracted a significant amount of interest because they will impact the binding ability, lipophilicity, metabolic stability, and chemical stability of the resulting molecules. Over the past few years, photocatalytic trifluoromethylation of aryl alkenes has been reported, which typically requires precious Ru/Ir-containing photocatalytic systems. Herein, we report a metal-free organic photocatalyst composed of a bibenzothiazole core and two imine-bridged methoxyphenyl substituents (dBIP–OMe), which is able to drive trifluoromethylative bifunctionalization of alkenes photocatalytically without the use of any sacrificial reagents. Mechanistic studies reveal two consecutive single-electron-transfer steps between the exciteddBIP–OMe*, the CF3precursor (Umemoto’s reagent), and the alkene substrate. Substrate scope studies demonstrated that our trifluoromethylative bifunctionalization strategy usingdBIP–OMeis applicable for both aryl and aliphatic alkenes. Furthermore, a variety of nucleophiles, such as H2O, acetate, cyanide, azide, etc., can be readily incorporated into the carbocation intermediate once the foremost trifluoromethylation step is accomplished, substantially broadening the application scope of this photocatalytic method. Finally, taking advantage of the two-photon absorption capability ofdBIP–OMein the near-infrared region, we demonstrated that the hydroxytrifluoromethylation of styrene could be achieved using an inexpensive 740 nm LED as the sole light source.