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Programmable Ether Synthesis Enabled by Oxa-Matteson Reaction

Qiqiang Xie and Guangbin Dong*

*Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States, Email: gbdonguchicago.edu

Q. Xi, G. Dong, J. Am. Chem. Soc., 2022, 144, 8498-8503.

DOI: 10.1021/jacs.2c03621



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Abstract

An oxa-Matteson reaction enables sequential oxygen and carbenoid insertions into diverse alkyl- and arylboronates to provide a wide range of boron-substituted ethers. The utilities of this method are demonstrated in the the asymmetric synthesis of an acetyl-CoA-carboxylase inhibitor, and the programmable construction of polyethers.


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proposed mechanism



General Procedures for the Oxa-Matteson Reaction

General procedure A: To a flame-dried 10 mL culture tube were added amine oxide (27.4 mg, 0.2 mmol, 1.0 equiv), THF (2.0 mL), and RBpin (0.2 mmol, 1.0 equiv). The mixture was stirred at T1 for t1 hours. After cooling to room temperature, CH2Br2 (28 μL, 0.4 mmol, 2.0 equiv) was added. The reaction mixture was cooled to -78C and nBuLi (0.36 mmol, 1.8 equiv) was added dropwise under N2 atmosphere. The reaction was stirred at -78C for 30 minutes and then room temperature for 30 minutes. DMSO (1.0 mL) was added, and the mixture was stirred at 70C for 10 hours. The mixture was diluted with H2O (40 mL) and extracted with Et2O (20 mL x 2). The combined organic phase was washed with H2O (50 mL x 2) and brine (50 mL), dried over Na2SO4, and filtered. The solvent was removed under vacuum and the residue was dissolved in MeOH (2.0 mL). KHF2 (0.66 mmol, 3.3 equiv, 0.15 mL, 4.5 M aq.) was added. The mixture was stirred at room temperature for 3 hours before the solvent was removed under vacuum. The residue was re-dissolved in 50% aq. MeOH (8.0 mL) and the solvent was evaporated again. The dissolution-evaporation cycles were repeated 3 times. The obtained solid residue was washed with Et2O (10 mL x 2) to remove organic impurities. The solid residue was then extracted with anhydrous CH3CN. The combined organic washings were collected and concentrated under vacuum to give the desired trifluoroborate salt.


Key Words

ethers, aryl ethers, alkyltrifluoroborates, Matteson reaction


ID: J48-Y2022