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Palladium-Catalyzed Remote Hydro-Oxygenation of Internal Alkenes: An Efficient Access to Primary Alcohols

Xiang Li, Xintuo Yang, Pinhong Chen and Guosheng Liu*

*Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China, Email: gliumail.sioc.ac.cn

X. Li, X. Yang, P. Chen, G. Liu, J. Am. Chem. Soc., 2022, 144, 22877-22883.

DOI: 10.1021/jacs.2c11428


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Abstract

In a remote hydro-oxygenation of alkenes under palladium catalysis, both terminal and internal alkenes are suitable to yield the corresponding linear alcohols efficiently. A compatible SelectFluor/silane redox system plays an essential role for the excellent chemo- and regioselectivities. The reaction features a broad substrate scope and excellent functional group compatibility.


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General procedures for the synthesis of linear alcohols

For terminal alkenes

Pd(O2CCF3)2 (33.2 mg, 0.1 mmol, 10 mol%) and L4 (29.3 mg, 0.12 mmol, 12 mol%) were weighted into an oven-dried sealed tube (50.0 mL) and stirred in a mixture solvent of CH3CN and DCM (3:7, 10 mL) for 15 minutes. under an argon atmosphere. Then, alkene substrate (1.0 mmol, 1.0 equiv.), NaO2CCF3 (408.2 mg, 3.0 mmol, 3.0 equiv), Selectfluor (1.1 g, 3.0 mmol, 3.0 equiv) and iPr3SiH (633.4 mg, 4.0 mmol, 4.0 equiv) were added sequentially to above solution. Then the mixture was stirred at room temperature for 36 h under an argon atmosphere. Note: NaO2CCF3 needs to be ground to powder in the glovebox. After the alkene substrate was consumed, K2CO3 (276.0 mg, 2.0 mmol, 2.0 equiv.) and CH3OH (5.0 mL) were added to the reaction. And the mixture was stirred for another 6 hours. After that, the solvent was removed under vacuum and the residue was purified by column chromatography on silica gel with a gradient eluent of petrol ether / ethyl acetate or DCM / ethyl acetate to afford products.

For internal alkenes

Pd(O2CCF3)2 (33.2 mg, 0.1 mmol, 10 mol%) and L8 (34.1 mg, 0.12 mmol, 12 mol%) were weighted into an oven-dried sealed tube (50.0 mL) and stirred in a mixture solvent of 3 and DCM (3:7, 10 mL) for 15 minutes under an argon atmosphere. Then, alkene substrate (1.0 mmol, 1.0 equiv.), NaO2CCF3 (408.2 mg, 3.0 mmol, 3.0 equiv), Selectfluor (1.1 g, 3.0 mmol, 3.0 equiv) and iPr3SiH (633.4 mg, 4.0 mmol, 4.0 equiv) were added sequentially. Then the mixture was stirred at 10 C for 60 h under an argon atmosphere. Note: NaO2CCF3 needs to be ground to powder in the glovebox. After the alkene substrate was consumed, K2CO3 (276.0 mg, 2.0 mmol, 2.0 equiv.) and CH3OH (5.0 mL) were added to the reaction. And the mixture was stirred for another 6 hours at room temperature. After that, the solvent was removed under vacuum and the residue was purified by column chromatography on silica gel with a gradient eluent of petrol ether / ethyl acetate or CH2Cl2 / ethyl acetate to afford products.


Key Words

hydroxylation, Selectfluor, silanes


ID: J48-Y2022