Hexafluoropropylene oxide dimer acid (HFPO-DA, ammonium salt with trade name: GenX) has been recently detected in river water worldwide. There are significant concerns about its persistence, and potential adverse effects to the biota. In this study, the degradability of GenX by typical advanced redox technologies (UV/persulfate and UV/sulfate) is investigated. Results demonstrate that <5% GenX is oxidized after 3 h in UV/persulfate system, which is much lower than ∼27% for PFOA. In comparison, GenX can be readily degraded and defluorinated by hydrated electron (e) generated by UV/sulfite system. Specifically, GenX is not detectable after 2 h, and >90% of fluoride ion is recovered 6 h later. This is attributed to the accumulation and subsequent degradation of CFCFCOOH and CFCOOH, which are stable intermediates of GenX degradation. Mechanistic investigations suggest that the etheric bond in the molecule is a favorable attack point for the e. Such finding is corroborated by quantum chemical calculations. The side CF- at the α-carbon probably acts as an effective barrier that prevents GenX from being cleaved by SO• or OH• at its most sensible point (i.e. the carboxyl group). This study illustrates that reduction by UV/sulfite might be a promising technology to remove GenX from contaminated water.

This review summarizes the recent advance in transition-metal-catalyzed carbene insertion to C–H bonds, forming diverse C–C bonds.

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We herein report the hydrogenation of substituted aryl-and heteroaryl boronate esters for the selective synthesis of cis-substituted borylated cycloalkanes and saturated heterocycles.Acyclic (alkyl)(amino)carbene-ligated rhodium complex with two dimethyl groups at the ortho-alkyl scaffold of the carbene showed high reactivity in promoting the hydrogenation, therebye nabling the hydrogenation of (hetero)arenes with retention of the synthetically valuable boronate group. This process constitutes ac lean, atom-economic,a swell as chemo-and stereoselective route for the generation of cisconfigured, diversely substituted borylated cycloalkanes and saturated heterocycles that are usually elusive and difficult to prepare.

Carbon–carbon bond formation is among the most important reactions in organic synthesis. Reconstruction of a carbon–carbon bond through ring-opening C–C bond cleavage of a strained carbocycle usually occurs via a thermodynamically preferable pathway. However, carbon–carbon bond formation through thermodynamically less favorable C–C bond cleavage has seldom been documented. Herein, we disclose an unusual C–C bond cleavage of cycloketone oxime esters for [4+1] annulation. Under anaerobic copper­(I) catalysis, cycloketone oxime esters underwent regioselective, thermodynamically less favorable radical C–C bond cleavage followed by annulation with enaminothiones; that is, α-thioxo ketene N,S-acetals efficiently affording 2-cyanoalkyl-aminothiophene derivatives. Cyclobutanone, -pentanone, -hexanone, and -heptanone oxime esters could act as the effective C1 building blocks in the annulation reaction. An iminyl radical mechanism is proposed for the rare C–C bond cleavage/[4+1] annulation cascade.

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