Enantioselective Fluorination of α-Substituted β-Diketones Using β,β-Diaryl Serines
Samira Poorsadeghi, Katsuki Endo and Satoru Arimitsu*
*Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Senbaru 1, Nishihara, Nakagami, Okinawa 903-0213, Japan,
Email: arimitsu
sci.u-ryukyu.ac.jp
S. Poorsadeghi, K. Endo, S. Arimitsu, Org. Lett., 2022, 24, 420-424.
DOI: 10.1021/acs.orglett.1c04104
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Abstract
A β,β-diaryl serine catalyzes an enantioselective fluorination of α-substituted β-diketones to afford the corresponding fluorinated products in very good yields with excellent enantioselectivity. The CO2H group of the primary amine organocatalyst plays an important role in inducing the high enantioselectivity. Products could be converted into diols, aldols, and allylic fluorides without racemization.
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proposed transition state
General procedure for an enantioselective fluorination of α-substituted β-diketones
To a solution of α-branched β-diketone (0.1 mmol, 1.0 equiv) in THF (0.2 mL, 0.5 M) was added catalyst (20 mol%) and Selectfluor (0.2 mmol, 2.0 equiv) at room temperature. The resulting reaction mixture was stirred at 40 °C using an oil bath until TLC showed that the ester was totally consumed. The reaction mixture was quenched by sat. NaHCO3 and extracted with EtOAc. The combined organic phase was washed with brine and dried over MgSO4. The organic layer was filtered and concentrated with the rotary evaporator. The residue was purified by a silica gel flash chromatography to afford the desired fluorinated product.
K. Endo, D. Tomon, S. Arimitsu, J. Org. Chem., 2023, 88, 9037-9045.
Key Words
fluorination, Selectfluor, organocatalysis
ID: J54-Y2022
