Although atomically dispersed Fe-N 4 on carbon materials (Fe-NC) have enormous potential for the oxygen reduction reaction (ORR), precise control over the electronic structure of Fe to enhance the catalytic performance and a full understanding of the catalytic mechanism remain elusive. Herein, a novel approach is designed to boost the kinetic activity of single Fe-N 4 centers by controlling S-doped content and species (namely, thiophene-like S and oxidized S). Due to confinement and catalysis effects, the innovative strategy of combining a Mg(OH) 2 template with KOH activation preferentially generates oxidized S and simultaneously constructs porous carbon with a high Fe loading (2.93 wt%) and hierarchical pores. Theoretical calculations suggest that neighboring S functionalities can affect the electronic configurations of Fe-N 4 sites and increase the electron density around Fe atoms, thereby optimizing the adsorption energy of intermediates and substantially accelerating reaction kinetics, following the trend: oxidized S doped > thiophenelike S doped > pristine Fe-N 4 . Benefiting from high activity and accessibility of Fe-N 4 sites, the optimal FeNC-SN-2 electrode displays impressive ORR activity with large power density while maintaining outstanding durability in Zn-air batteries and microbial fuel cells. The work paves the way to prepare stable single-atom metal-N x sites with heteroatom-doping for diverse highperformance applications.

A Cu-catalyzed asymmetric detrifluoroacetylative aldol addition reaction of 2-fluoro-1,3-diketones/hydrates to aldehydes in the presence of base and chiral bidentate ligand was developed. The reaction was carried out under convenient conditions and tolerated a wide range of substrates, resulting in fluorinated quaternary stereogenic α-fluoro-β-hydroxy ketone products with good chemical yields, diastereo- and enantioselectivities. This catalytic asymmetric detrifluoroacetylative aldol addition reaction provides a new approach for the preparation of biologically relevant products containing C-F quaternary stereogenic centers.

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CF3-containing chiral imines readily react with α,α-difluoroenolates affording a novel type of β-keto-amino compounds featuring the R-CO-CF2-CH(NH2)-CF3 moiety. The reactions feature exceptional generality allowing preparation of various aromatic, hetero-aromatic and aliphatic derivatives in high yields and diastereoselectivity. The products are configurationally stable and can be transformed to more functionalized complex compounds.