Single-Atom Manganese-Catalyzed Oxygen Evolution Drives the Electrochemical Oxidation of Silane to Silanol.

The oxygen evolution reaction (OER), characterized by a four-electron transfer kinetic process, represents a significant bottleneck in improving the efficiency of hydrogen production from water electrolysis. Consequently, extensive research efforts have been directed towards identifying single-atom electrocatalysts with exceptional OER performance. Despite the comprehensive understanding of the OER mechanism, its application to other valuable synthetic reactions has been limited. Herein, we leverage the MOOH intermediate, a key species in the Mn-N-C single-atom catalyst (Mn-SA@NC), which can be cyclically delivered in the OER. We exploit this intermediate' s capability to facilitate electrophilic transfer with silane, enabling efficient silane oxidation under electrochemical conditions. The SAC electrocatalytic system exhibits remarkable performance with catalyst loadings as low as 600 ppm and an exceptional turnover number of 9132. Furthermore, the catalytic method demonstrates stability under a 10 mmol flow chemistry setup. By serving as an OER electrocatalyst, the Mn-SA@NC drives the entire reaction, establishing a practical Mn SAC-catalyzed organic electrosynthesis system. This synthesis approach not only presents a promising avenue for the utilization of electrocatalytic OER but also highlights the potential of SACs as an attractive platform for organic electrosynthesis investigations.

Selective Difunctionalization of Unactivated Aliphatic Alkenes Enabled by a Metal-Metallaaromatic Catalytic System.

The design of organometallic catalysts is crucial in the development of catalytic reactions. Herein, we describe a heterometallic [Os-Cu] complex with the characteristics of bimetallics, metallaaromatics, and pincer complexes. This complex serves as a highly effective catalyst for selective amino- and oxyselenation of unactivated alkenes. More than 80 examples including challenging substrates of unsymmetric aliphatic alkenes and amine-based nucleophiles in such reactions are provided. These reactions produce 1,2-difunctionalized products with good yields and high levels of chemo-, regio-, and stereoselectivity. Our studies revealed the following: (i) The usually inert osmium center activates the N- or O-centered nucleophiles. (ii) The copper-osmium bonding and its cooperative effects play essential roles in control the selectivity by bringing the reaction components into close proximity. (iii) The metallaaromatic moiety helps to stabilize the intermediate. These findings provide a versatile platform for catalyst design based on metal-metallaaromatic cooperative effects that have not been attained previously with bimetallic complexes.

Condensed Osmaquinolines with NIR-II Absorption Synthesized by Aryl C-H Annulation and Aromatization.

The structural design and tuning of properties of metallaaromatics are crucial in materials and energy science. Herein, we describe the rapid synthesis of tetracyclic metallaaromatics containing quinoline and pentalene motifs fused by a metal-bridged fragment. These unique compounds display remarkably broad absorption, enabling for the first time the absorption of metallaaromatics to reach the second near-infrared (NIR-II) bio-window. The formation of osmaquinoline unit involves an unconventional C(sp2 )-C(sp3 ) coupling promoted by AgBF4 to achieve [3+3] cycloaddition. The introduction of cyclic dπ -pπ conjugation and extension of the aromatic π-framework can effectively shrink the HOMO-LUMO gap, thus broadening the absorption window. The considerable photothermal conversion efficiency (PCE) in both the NIR-I and NIR-II windows, the high photothermal stability and the excellent electrochemical behavior suggest many potential applications of these condensed metallaquinolines.

Copper-Metallized Porous N-Heterocyclic Carbene Ligand Polymer-Catalyzed Regio- and Stereoselective 1,2-Carboboration of Alkynes.

Alkenylboronates are highly versatile building blocks and valuable reagents in the synthesis of complex molecules. Compared with that of monosubstituted alkenylboronates, the synthesis of multisubstituted alkenylboronates is challenging. The copper-catalyzed carboboration of alkynes is an operationally simple and straightforward method for synthesizing bis/trisubstituted alkenylboronates. In this work, a series of copper-metallized N-Heterocyclic Carbene (NHC) ligand porous polymer catalysts are designed and synthesized in accordance with the mechanism of carboboration. By using CuCl@POL-NHC-Ph as the optimal nanocatalyst, this study realizes the ß-regio- and stereoselective (syn-addition) 1,2-carboboration of alkynes (regioselectivity up to >99:1) with satisfactory yields and a wide range of substrates. This work not only overcomes the selectivity of carboboration but also provides a new strategy for the design of nanocatalysts and their application in organic synthesis.

Electrochemically Promoted Three-Component Reaction to N-Sulfonyl Amidines.

In this study, a multicomponent reaction via the Mannich intermediate was developed using methanol, secondary amine, and sulfonamide as starting materials. This method uses methanol as a green C1 source. The substrate scope is wide, and the yield is good. The mechanistic study shows that methanol generates formaldehyde under electrochemical conditions, and sulfonyl amidine as a nucleophile reacts with Schiff base intermediates to form N-sulfonyl amidine in a single step.

Electrochemical synthesis of ß-difluoromethylamide compounds by N-benzenesulfonylacrylamide with difluorine reagents.

A mild and efficient electrochemical method for radical addition, cyclization, and migration reaction was described in this work. A difluoromethyl radical was produced by anodizing CF2HSO2Na. The resulting product was then added to olefin, underwent Smiles cyclization, and migrated to form ß-difluoromethamide compounds after the release of SO2. The process was free from metals and catalysts, gram-grade, and resistant to a variety of electron-rich substrates.

Electrochemical Promoted Three-Component Trifluoromethylation/Spirocyclization Reaction of N-Arylsulfonylacrylamides to 4-Azaspiro[4.5]decanes.

An electrochemical facilitated three-component trifluoromethylation/spirocyclization reaction of N-(arylsulfonyl)acrylamides, CF3SO2Na, and H2O has been developed. Without the requirement of chemical oxidants, a number of unexplored trifluoromethylated 4-azaspiro[4.5]decanes were obtained in satisfactory yields under mild conditions. This work provides a new synthetic strategy for fluorine-containing spirocyclic compounds and shows a new perspective for the reactivity study of N-(arylsulfonyl)acrylamides.

Copper-Catalyzed Decarboxylative/Click Cascade Reaction: Regioselective Assembly of 5-Selenotriazole Anticancer Agents.

A simple and efficient Cu-catalyzed decarboxylative/click reaction for the preparation of 1,4-disubstituted 5-arylselanyl-1,2,3-triazoles from propiolic acids, diselenides, and azides has been developed. The mechanistic study revealed that the intermolecular AAC reaction of an alkynyl selenium intermediate occurred. The resulting multisubstituted 5-seleno-1,2,3-triazoles were tested for in vitro anticancer activity by MTT assay, and compounds 4f, 4h, and 4p showed potent cancer cell-growth inhibition activities.