Direct C(sp)-H/Si-H Cross-Coupling via Copper Salts Photocatalysis
Qi-Chao Gan, Zi-Qi Song, Chen-Ho Tung and Li-Zhu Wu*
*Technical Institute of Physics and Chemistry, Chinese Academy
of Sciences, Beijing 100190, P. R. China, Email: lzwu
mail.ipc.ac.cn
Q.-C. Gan, Z.-Q. Song, C.-H. Tung, L.-Z. Wu, Org. Lett., 2022, 24, 5192-5196.
DOI: 10.1021/acs.orglett.2c02022
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Abstract
Visible-light irradiation mediates the synthesis of alkynylsilanes in very good yields from alkynes and silanes in the presence of CuCl as precatalyst. A large scale flow reaction and late-stage functionalization of natural products show the potential of the transformation.
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proposed mechanism
Details
The document reports the first example of C(sp)−H/Si−H cross-coupling via photocatalysis using copper salts. This method utilizes visible-light irradiation to activate CuCl and alkynes with silane, producing alkynylsilanes in good to excellent yields. The process is efficient, cost-effective, and environmentally friendly, leveraging cheap and readily available starting materials. The study highlights the potential of this transformation in practical organic synthesis, including large-scale reactions and late-stage functionalization of natural products. The optimal reaction conditions involve using 5 mol % of CuCl and 1.5 equivalents of Ph(CO)O2tBu under blue-light irradiation in an argon atmosphere. The method tolerates a broad spectrum of terminal aryl alkyne partners and various silanes, although primary and secondary silanes or those with strong electron-donating groups did not react. Mechanistic studies suggest that in-situ-generated Cu(I)-phenylacetylide is the key photocatalyst, with single-electron-transfer processes playing a crucial role. The approach opens new avenues for C(sp)−H silylation by photocatalysis, demonstrating significant potential for future applications in organic synthesis.
Key Words
alkynylsilanes, photochemistry, tert-butyl peroxybenzoate
ID: J54-Y2022
