Photoinduced Efficient Catalytic α-Alkylation Reactions of Active Methylene and Methine Compounds with Nonactivated Alkenes

Yasuhiro Yamashita*, Yoshihiro Ogasawara, Trisha Banik and Shu̅ Kobayashi*

*Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan, Email: shu_kobayashichem.s.u-tokyo.ac.jp

Y. Yamashita, Y. Ogasawara, T. Banik, S. Kobayashi, J. Am. Chem. Soc., 2023, 145, 22735-22744.

DOI: 10.1021/jacs.3c07436

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Abstract

Combining an organophotocatalyst and lithium thiophenoxide in a Lewis acid/Brønsted base/hydrogen atom transfer (HAT) multifunctional catalytic system enables highly efficient α-alkylation reactions of active methylene and methine compounds with nonactivated alkenes under blue-light irradiation. The reaction was performed with a higher degree of efficiency under continuous-flow.

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proposed mechanism

4CzIPN

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Alkylation reactions of active methylene compounds with alkenes

The reaction mixture was prepared inside a grove box filled with argon gas. LiSPh (2.3 mg, 0.020 mmol) was placed in a well-dried 15 mL pyrex tube (Diameter: 14 mm), and degassed anhydrous THF (2.0 mL) and dimethyl malonate (1.10 mmol) were added. Subsequently, 1-decene (1.00 mmol), 4CzIPN (3.9 mg, 0.0050 mmol), and degassed anhydrous acetonitrile (MeCN, 3.0 mL) were added. After the tube was sealed with a septum, the reaction mixture was stirred at room temperature under blue-light irradiation for 12 h. The resulting mixture was quenched with H₂O and extracted with DCM (20 mL x 3). The combined organic layer was dried over anhydrous Na₂SO₄. After filtration and concentration under reduced pressure, the crude product was purified by column chromatography on silica gel or PTLC to afford the desired product.

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Key Words

active methylene compounds, photochemistry

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ID: J48-Y2023