Benson J. Jelier

A Convenient Route to Tetraalkylammonium Perfluoroalkoxides from Hydrofluoroethers

Hydrofluoroethers are shown to alkylate tertiary amines readily under solvent-free conditions, affording valuable tetraalkylammonium perfluoroalkoxides bearing α-fluorines. The reaction of R(F)CF2-OCH3 (R(F)=CF2CF3, CF2CF2CF3, and CF(CF3)2) with NR(1)R(2)R(3) produces twenty new α-perfluoroalkoxides, [(CH3)NR(1)R(2)R(3)][R(F)CF2O] under mild conditions. These α-perfluoroalkoxides are easy to handle, thermally stable, and can be used for the perfluoroalkoxylation of benzyl bromides.

Radical Trifluoromethoxylation of Arenes Triggered by a Visible-Light-Mediated N−O Bond Redox Fragmentation

A simple trifluoromethoxylation method enables non-directed functionalization of C-H bonds on a range of substrates, providing access to aryl trifluoromethyl ethers. This light-driven process is distinctly different from conventional procedures and occurs through an OCF3 radical mechanism mediated by a photoredox catalyst, which triggers an N-O bond fragmentation. The pyridinium-based trifluoromethoxylation reagent is bench-stable and provides access to synthetic diversity in lead compounds in an operationally simple manner.

Exposing the Origins of Irreproducibility in Fluorine NMR Spectroscopy

Fluorine chemistry has taken a pivotal role in chemical reaction discovery, drug development, and chemical biology. NMR spectroscopy, arguably the most important technique for the characterization of fluorinated compounds, is rife with highly inconsistent referencing of fluorine NMR chemical shifts, producing deviations larger than 1 ppm. Herein, we provide unprecedented evidence that both spectrometer design and the current unified scale system underpinning the calibration of heteronuclear NMR spectra have unintentionally led to widespread variation in the standardization of 19 F NMR spectral data. We demonstrate that internal referencing provides the most robust, practical, and reproducible method whereby chemical shifts can be consistently measured and confirmed between institutions to less than 30 ppb deviation. Finally, we provide a comprehensive table of appropriately calibrated chemical shifts of reference compounds that will serve to calibrate 19 F spectra correctly.

Mapping Perfluoroalkyl Effects in Togni-Type Reagents by Thermolysis

We present the thermolysis of cyclic hypervalent iodine(III) perfluoroalkyl transfer reagents carried out in standard GC-MS instrumentation. Through heating, these structures undergo fragmentation to afford perfluoroalkyl radicals F2n+1 Cn. and each reagent can be characterized by means of a threshold temperature, TIP (n). This parameter TIP (n) not only reflects the stability of the F2n+1 Cn -I bond, but potentially also carries information regarding fundamental properties of the linear perfluoroalkyl chains.