The decarboxylative transformation of carboxylic acids is a valuable tool for C-C and C-X bond construction owing to its ubiquitous nature and structural diversity. However, traditional two-electron decarboxylation strategies require harsh reaction conditions and suffer from a limited substrate scope, which severely hamper their application in organic synthesis. In contrast, by integrating with photocatalytic or electrocatalytic processes, a single electron transfer-induced decarboxylative strategy provides a mild and general platform, enabling a series of C-C and C-X cross-coupling reactions with bench-stable carboxylic acids. Herein, we report a copper-catalyzed direct decarboxylative alkynylation of arylacetic acids under electrophotochemical conditions in which the copper catalyst not only induced the decarboxylation via a ligand-to-metal charge-transfer (LMCT) process but also captured the alkyl radical and coupled it with an alkyne to access the alkynylation product. The introduction of electricity provides this mild and green protocol with a better functional group tolerance that makes it a good alternative strategy for carboxylic acid functionalization in organic synthesis and bioconjugation.
Postsynthetic modification of a series of hexacationic organic cages containing pyridinium and hydrazone groups gave a new family of neutral organic cages through a high-yielding single-step reduction reaction. The reaction selectively reduces all six pyridinium rings to 1,2,3,6-tetrahydropyridines but leaves the hydrazone C═N bond untouched. The neutral cages display strong sulfate binding to give cage·(SO42-)2 complexes in DMSO.
tBuONO was used as an efficient organo co-catalyst for the palladium-catalyzed oxidative α,β-dehydrogenation of ketones. Molecular oxygen was used as the clean and sole oxidant. Both linear and cyclic α,β-unsaturated ketones could be efficiently prepared under aerobic catalytic conditions directly from the corresponding saturated ketones. No toxic transition metal co-catalyst or polar solvent is required. The organic nitrite redox co-catalyst and alcohol solvent play key roles for realizing this catalysis.
A photochemical strategy enabling tandem cyclization and dearomatization of ortho-sulfonamide-tethered alkylidenecyclopropanes via N-centered radicals has been developed under metal-free conditions. The reaction employs an organic fluorophore 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as a photocatalyst. This mild and operationally simple photocatalytic system demonstrates that the sulfonamidyl-radical-mediated intramolecular olefin amination effectively integrates radical ring opening with dearomatization pathways, thereby facilitating the synthesis of diverse fused seven-membered cyclic sulfonamides with a broad substrate scope, high regioselectivity, and excellent product diversity.
Photolabile protecting groups (PPGs) enable spatiotemporal control of chemical and biological processes, yet multistimuli-regulated systems remain rare. Here we report a triple-stimuli platform integrating light, base, and acid to control PPG release. Photoirradiation of diarylethenes (DAEs) under basic conditions generates stable 9,10-dihydrophenanthrene (9,10-DHP) intermediates that activate hemiaminal ethers and undergo acid-promoted aromatization to release the alcohol group. Distinct fluorescence changes allow real-time monitoring in both organic and aqueous media.
A photocatalytic radical chloro-fluorosulfonylation of alkynyl cyclohexadienones with FSO2Cl using organic dye eosin Y as the photocatalyst is reported. The reaction proceeds smoothly with excellent stereoselectivity via atom transfer radical addition to afford multifunctionalized bicyclic alkenyl sulfonyl fluorides. Downstream reactions of the resulting bicyclic products showcase an efficient approach to access diverse functionalized sulfonyl fluorides from readily available phenols.
A green and sustainable synthetic protocol for γ-lactams is developed herein via metal-free three-component photocatalysis using pure water as the sole solvent. This strategy combines the advantages of visible-light activation, one-pot multicomponent coupling, and aqueous-phase synthesis, overcoming the drawbacks of traditional methods such as organic solvent pollution, transition metal residues, and harsh conditions. Employing inexpensive and readily available N-arylglycines, acrylates, and 1,1-diarylethylenes as starting materials, this method enables two consecutive C-C bond-forming events to access a variety of valuable yet otherwise difficult-to-access γ-lactams and γ-aminobutyric acid (GABA) derivatives. Mechanistically, photoredox activation of N-arylglycines generates α-amino radicals upon decarboxylation, which undergo sequential radical addition with acrylic phenol esters and 1,1-diarylethylenes, followed by cyclization to form the pyrrolidinone core. The synthetic utility is further demonstrated by the preparation of δ-amino alcohols and γ-aminobutyric acids together with preliminary asymmetric synthesis studies.
Reported herein is Rh-catalyzed C-H activation of indoles en route to redox-neutral coupling with alkyne-tethered N-cyanosulfonamides. The transformation enables chemodivergent C-C coupling via selective migration of either the cyano or sulfonyl group in alkyne-tethered N-cyanosulfonamide, affording C-H olefination or heteroarylation, respectively. The reaction enables one-pot construction of multiple chemical bonds, exhibits broad functional group tolerance, and is accompanied by mechanistic studies.
A family of bidentate boron complexes based on a 2,1-borazaronaphthalene scaffold, containing both tri- and tetracoordinate boron centers, were synthesized. These complexes exhibit tunable absorption-emission and solid-state fluorescence, accompanied by large Stokes shifts (4100-9200 cm-1) due to intramolecular charge transfer. Notably, binding of fluoride at the tricoordinate boron center triggers distinct colorimetric and fluorometric responses with a high association constant (Ka ≈ 3 × 104 M-1), which highlights their potential for fluoride detection.
Metal-free, silyl-triflate-catalyzed formal inverse-electron-demand Diels-Alder annulation of isoquinolines with ynamides enables the divergent synthesis of 2-aminonaphthalenes and 2-amino-1-naphthonitriles. The 3-substituent on isoquinoline dictates product selectivity: H or Me leads to nitrile extrusion, whereas Cl or Br triggers HX elimination. The transformation features a broad substrate scope, good scalability, and unified catalytic cycle involving substituent-directed bifurcation from a common bicyclic imine intermediate. This work offers a practical, metal-free route to functionalized naphthalenes and new insights into Lewis-acid-catalyzed annulations.
Phosphine-boryl radicals remain less well-studied because their parent phosphine-boranes are highly stable under oxidative conditions. Herein, we report a strategy for generating phosphine-boryl radicals facilitated by radical precursors through an appropriate molecular design. Incorporating a proximal oxidant into a phosphine-borane facilitates the formation of the corresponding boron-centered radical through proton-coupled intramolecular electron transfer. The resulting phosphine-boryl radical can be used to generate an alkyl radical via halogen atom transfer.
How to stabilize the metastable all/long catenated nitrogen atom system is a great challenge. In this work, a novel "aza-heteroaromatic-sealed" strategy to seal an unstable N10B structure by two 4-nitro-1,2,3-triazole scaffolds and obtain stable F-N10B [1,2-bis(5-(4-nitro-2H-1,2,3-triazol-2-yl)-2H-tetrazol-2-yl)diazene] under mild reaction conditions was exhibited. As a benefit from increased p-π interactions, non-classical hydrogen bonds (O···H-C), bond dissociation energy, and aromatic properties, F-N10B shows the best safety among the all reported N10-type energetic compounds (Td = 160 °C, IS = 1.5 J, and FS = 7 N). Thus, almost all characterizations can be performed under ambient conditions (NMR, IR, elemental analysis, scanning electron microscopy, and single-crystal X-ray diffraction). This work successfully addressed the challenge of achieving stable termination for the highly unstable structure containing eight catenated nitrogen atoms, contributing to the advancement of the understanding in the discipline of metastable high-entropy and fully nitrogenous energetic materials.
A relay Pd(0)/Brønsted base-catalyzed cascade reaction between N-trifluoroethyl isatin ketimines and propargylic carbonates is reported, proceeding through Pd(0)-catalyzed allenylation followed by Brønsted base-directed deprotonation, 5-endo-trig cyclization, ring expansion, and aromatization. A broad range of pyrrolopyrimidinone frameworks are furnished in high yields with good tolerance toward a variety of functional groups.
Unsymmetrical chiral 1,2-diamines are important motifs widely present in pharmaceuticals, chiral auxiliaries, and ligands/catalysts. A novel and efficient strategy for the modular synthesis of unsymmetrical chiral 1,2-diaryl ethylenediamines via chiral diboron-templated reductive cross-coupling of aldimines has been established. By leveraging both steric and concentration effects, good chemoselectivity and enantioselectivity have been achieved and homocoupling side-reactions are effectively inhibited. The method exhibits good functional group tolerance and scalability, offering a practical and versatile route to unsymmetrical chiral 1,2-diamines.
A three-component synthesis of [60]fullerene-fused tetrahydropyridines was developed via the reaction of [60]fullerene with chalcones in the presence of magnesium nitride as the nitrogen source under ball-milling conditions. This method utilizes easily available starting materials, eliminates the need for metal catalysts and ligands, and delivers the products under mild conditions. Furthermore, one of the synthesized products was successfully employed as an interlayer in perovskite solar cells to increase the power conversion efficiency.
We report a photoredox desilyloxylative sulfonylation of allyl silyl ethers with thiosulfonates that integrates both silyloxy group deletion and isomerization into the sulfonylation reaction for the synthesis of (E)-allylic sulfones in a highly stereoselective and regioselective manner. This process involves photoinduced synthesis of the sulfonyl radicals from homolytic cleavage of thiosulfonates, followed by radical addition across the alkene moiety and the silyoxyl radical elimination cascades. Notably, this method features a broad substrate scope, a good functional group tolerance, an excellent stereo/regioselectivity, and mild, simple reaction conditions. Furthermore, the resulting products can be transformed into highly valuable molecules possessing E-alkenyl groups.
Difunctionalization of internal alkynes provides prominent methods for the modular construction of tetrasubstituted alkenes. However, the development of an enantioselective version of such transformation remains elusive. We present herein an enantioselective nickel-catalyzed arylative coupling reaction of simple alkynes with N-sulfonylimines and arylboronic reagents. This asymmetric three-component transformation furnished a wide range of enantioenriched tetrasubstituted allylic amines with excellent regioselectivity and stereoselectivity under mild conditions.
A visible-light photocatalytic method for the C5-selective monohydrodechlorination of 4,5-dichloropyridazinones is described. Using Eosin Y-Na2 and DIPEA, the reaction proceeds under mild conditions and tolerates a wide range of N2 substituents and functional groups. Mechanistic studies support a single-electron transfer pathway involving a C5-centered radical, with DFT calculations revealing that the inherently weaker C5-Cl bond (87.1 vs 89.1 kcal/mol) accounts for the selectivity, while kinetic control from neutral DIPEA dictates the reaction outcome.
Glycosyltransferase AcbI from Pantoea agglomerans ZJU23 was first expressed and biochemically elucidated to catalyze the last-step glycosylation of herbicolin A (1) with antifungal activity. By AlphaFold2 prediction, molecular docking, and site-directed mutagenesis experiments, AcbI was hypothesized to function via a working model resembling the catalytic mechanism of type A glycosyltransferase, with the exception that the R75 residue in AcbI can electrostatically stabilize the leaving phosphate of UDP-d-Glc. Our findings provide novel highlights and tools for the glycosylation of cyclolipopeptides.
An o-nitroveratryloxycarbonyl-based solubilizing tag was developed to improve the chemical synthesis of poorly soluble peptides and proteins. Tag installation markedly enhances the aqueous solubility of hydrophobic peptide fragments, while allowing clean removal via UV irradiation. This strategy facilitates efficient handling of challenging fragments and supports downstream peptide ligation for the synthesis of hydrophobic proteins.