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Hydroalkylation of Unactivated Olefins via Visible-Light-Driven Dual Hydrogen Atom Transfer Catalysis

Guangyue Lei, Meichen Xu, Rui Chang, Ignacio Funes-Ardoiz* and Juntao Ye*

*Universidad de La Rioja, Madre de Dios 53, 26006 Logroņo, Spain; Shanghai Jiao Tong University, Shanghai 200240, China, Email: ignacio.funesaunirioja.es, juntaoyesjtu.edu.cn

G. Lei, M. Xu, R. Chang, I. Funes-Ardoiz, J. Ye, J. Am. Chem. Soc., 2021, 143, 11251-11261.

DOI: 10.1021/jacs.1c05852


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Abstract

Visible-light-driven dual HAT catalysis overcomes the inherent polarity-mismatch and achieves hydroalkylation of unactivated olefins using catalytic amounts of an amine-borane and an in situ generated thiol as the hydrogen atom abstractor and donor, respectively. The reaction is completely atom-economical and exhibits a broad scope.


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proposed mechanism

[Ir(dF(CH3)ppy)2(dtbbpy]BArF4



Typical Procedure:

To an oven-dried 15 x 50 mm vial containing a dry Teflon stir bar were charged with photocatalyst [Ir(dF(CH3)ppy)2(dtbbpy)]BArF4 (3.5 mg, 0.002 mmol), borane catalyst (7.9 mg, 0.04 mmol), and bis(2,4,6-triisopropylphenyl) disulfide [(TRIPS)2] (4.7 mg, 0.01 mmol). The vial was then brought into a N2-filled glovebox where dry PhCF3 (0.5 mL), dimethyl malonate (91.2 μL, 0.8 mmol, d = 1.16), and olefin (0.2 mmol) were added sequentially. The vial was sealed with a cap, removed from the glovebox, and placed approximately 5 cm away from a 40 W Kessil blue LED. The reaction mixture was then stirred with irradiation. A small fan was placed adjacent to the vial to maintain the reaction temperature at 25-30°C. The reaction mixture was monitored by thin-layer chromatography (TLC) and gas chromatography mass spectrometry (GC-MS). After the reaction reached completion, the crude mixture was concentrated under reduced pressure and purified by flash column chromatography on silica gel.


Key Words

hydrogen atom transfer, hydroalkylation, polar effect, active methylene compounds, Giese Reaction, photochemistry


ID: J48-Y2021