Bin Chen

Catalyst-free difunctionalization of alkene is achieved under visible light irradiation to form complex α-hydroxycarbonyls.

We report an efficient bimetallic Mo(IV)Fe(II) electrocatalyst that achieves highly selective nitrite-to-NO reduction. This catalyst demonstrates exceptional performance, with a record turnover frequency (TOF) of ∼10³ s^-1 and a Faradaic efficiency of 93.8%. Mechanistic studies integrating experimental and DFT analyses reveal that the Mo(IV) center preferentially binds NO over the Fe(II) site, preventing the catalytic cycle from terminating at a stable ferrous nitrosyl species. The synergistic interplay between the Fe and Mo centers enhances nitrite dynamic coordination and facilitates reductive N-O bond cleavage, highlighting the critical role of bimetallic synergism in lowering energy barriers and driving demanding exergonic reaction steps involving electron and proton transfer.

Cross-coupling acylation by direct aldehyde activation is ideal to construct a useful carbonyl motif. However, the strong C-H bond energy, short radical lifetime, and mismatched radical polarity render this reaction a huge challenge. Herein, the semiconductor quantum dots (QDs) interface is demonstrated to overcome the obstacles lying on the way to acylating alkene or alkylarene, directly activating the formyl C-H bond into an acyl radical. Further stabilization of the obtained radical species by the QD interface ensured their effective cross-coupling with the generated intermediate from the coupling partner. The interface of QDs was exemplified to execute photochemical transformation, showcasing a highly efficient and selective cross-coupling acylation reaction under extremely mild conditions.

Ring contraction in skeletal reorganization strategies is one of the most intriguing yet surprisingly challenging transformations. Herein, we report for the first time a ring contraction tandem sulfonation between saturated six-membered N-heterocyclic nitroxides and sulfonyl hydrazides to access sulfonated pyrrolidine derivatives by an electrochemical redox cascade under redox-neutral and metal-free conditions, which is unavailable via conventional synthetic approaches. This benign approach to sulfonated pyrrolidine derivatives has been further demonstrated by gram-scale preparation and pharmaceutical molecule synthesis under mild conditions.

Herein is the first example of photocatalytic cross-coupling of alkenes with aldehydes by a single catalyst without an external photosensitizer and any additives. Irradiation of the aromatic aldehyde and cobaloxime catalyst results in the formation of an acyl radical, which undergoes radical addition with alkene or indole and subsequently β-H elimination to afford alkenyl ketone. The reaction features cheap and readily available raw materials, a broad substrate scope, and mild conditions, even for late-stage derivatization of bioactive compounds.

Represented herein is the first 1,3-difunctionalization of alkenes via photocatalysis. A single cobaloxime is used to carry out two catalytic cycles in which cobaloxime is used not only as a photocatalyst to initiate the reaction but also as a metal catalyst for the β-H elimination process. Electron-deficient alkenes, electron-rich alkenes, and unactivated alkenes could be directly converted to 1,3-bisphosphorylated products, even unsymmetric 1,3-bisphosphorylated products, with only H₂ as a byproduct under extremely mild reaction conditions.

Represented herein is a simple thiol identified as an effective precursor to photochemically form a carbocation. Thanks to the thiyl radical rapid transformation to disulfide, which serves not only to stabilize the generated thiyl radical but also to allow the second electron transfer to form a carbocation. The resulting carbocations, including primary benzylic, secondary, and tertiary carbocations, can smoothly couple with nitrogen, oxygen, and carbon nucleophilic coupling partners as well as complex drug molecules, accompanied by elemental sulfur formation in air.

Photoredox catalytic processes offer the potential for precise chemical reactions using light and materials. The central determinant is identified as interfacial charge transfer, which simultaneously engenders distinctive behavior in the overall reaction. An in-depth elucidation of the main mechanism and highlighting of the complexity of interfacial charge transfer can occur through both diffusive and direct transfer models, revealing its potential for sophisticated design in complex transformations. The fundamental photophysics uncover these comprehensive applications and offer a clue for future development. This research contributes to the growing body of knowledge on interfacial charge transfer in photoredox catalysis and sets the stage for further exploration of this fascinating area of research.

Diels-Alder cycloaddition of anthracene with olefin is achieved in a homogeneous solution via energy transfer under visible light. A series of substrates including electroneutral styrene derivatives can be successfully converted into the corresponding cycloadducts in a head-to-head orientation with high to excellent yields. The high ortho-regioselectivity, mild condition, and broad substrate scope enable promising advances in organic transformation.

Direct sp³ C–H arylation with heteroarenes is a straightforward approach for accessing valuable heteroarene-containing molecules. Unlike the established approaches that generally require precious metal catalysts, directing groups, stoichiometric strong oxidants and high temperatures, we report herein a scalable and mild strategy for aliphatic C–H arylation with heteroarenes under photocatalyst-free and strong oxidant-free conditions. This photochemistry features a broad substrate scope, good to excellent yields, and extremely mild conditions. Spectroscopic studies reveal that protonated heteroarenes have light-absorbing ability to initiate alkyl radical formation from aliphatic C–H bonds under aerobic visible light irradiation.