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Palladium(II)-Catalyzed Enantioselective Hydrooxygenation of Unactivated Terminal Alkenes

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

*Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China, Email: pinhongchensioc.ac.cn, gliumail.sioc.ac.cn

X. Yang, X. Li, P. Chen, G. Liu, J. Am. Chem. Soc., 2022, 144, 7972-7977.

DOI: 10.1021/jacs.2c02753


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Abstract

In a Pd(II)-catalyzed enantioselective Markovnikov hydrooxygenation of unactivated terminal alkenes using a substituted pyridinyl oxazoline (Pyox) ligand, a (EtO)2MeSiH/BQ redox system is vital for the highly selective and efficient hydrooxygenation. This method provides efficient access to a broad range of optically pure alcohol esters from easily available alkenes with excellent enantioselectivities.

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Enantioselective hydrooxygentaion of terminal alkenes (procedure A)

Pd(OAc)2 (11.2 mg, 0.05 mmol, 10 mol%), ligand (20 mg, 0.075 mmol, 15 mol%) and BQ (162 mg, 1.5 mmol, 3 equiv.) were weighted into an oven-dried sealed tube (10 mL). Then, 1,1,2,2-tetrachloroethane (0.5 mL), 2-ethylbutyric acid (0.5 mL), alkene (0.5 mmol, 1.0 equiv.), H2O (0.15 mL) were added, then the diethoxymethylsilane (201 mg, 1.5 mmol, 3 equiv.) was added to the mixture. The mixture was stirred at 0C for 48 h. After the reaction was completed, saturated K2CO3 aq was added. The aqueous layer was extracted with ethyl acetate. The combined organic layers were dried over MgSO4 and concentrated in vacuo. The resulting residue was purified by flash chromatography on silica gel to afford the desired products.


Key Words

hydroxylation, BQ, (EtO)2MeSiH


ID: J48-Y2022