Electrochemically Driven Denitrative Cyanation of Nitroarenes.

A practical denitrative cyanation of feedstock nitroarenes under mild and transition metal-free reaction conditions has been developed. The key to success lies in the use of electrochemically driven, inexpensive ionic liquid N-methylimidazolium p-toluenesulfonate-promoted selective cathode reduction of nitroarenes to anilines, followed by diazoation, cathode reduction to form the aryl radical, and the essential radical cyanation process in one pot. Our protocol shows broad functional group tolerance and can be applied for the modification of bioactive targets.

Organomediated electrochemical fluorosulfonylation of aryl triflates via selective C-O bond cleavage.

Although aryl triflates are essential building blocks in organic synthesis, the applications as aryl radical precursors are limited. Herein, we report an organomediated electrochemical strategy for the generation of aryl radicals from aryl triflates, providing a useful method for the synthesis of aryl sulfonyl fluorides from feedstock phenol derivatives under very mild conditions. Mechanistic studies indicate that key to success is to use catalytic amounts of 9, 10-dicyanoanthracene as an organic mediator, enabling to selectively active aryl triflates to form aryl radicals via orbital-symmetry-matching electron transfer, realizing the anticipated C-O bond cleavage by overcoming the competitive S-O bond cleavage. The transition-metal-catalyst-free protocol shows good functional group tolerance, and may overcome the shortages of known methods for aryl sulfonyl fluoride synthesis. Furthermore, this method has been used for the modification and formal synthesis of bioactive molecules or tetraphenylethylene (TPE) derivative with improved quantum yield of fluorescence.

Selective Fluorosulfonylation of Thianthrenium Salts Enabled by Electrochemistry.

A practical electrochemically driven method for fluorosulfonylation of both aryl and alkyl thianthrenium salts has been disclosed. The strategy does not need external redox reagents or metal catalysts. In combination with C-H thianthrenation of aromatics, this method provides a new tool for the site-selective fluorosulfonylation of drugs.

Scalable Electrocatalytic Intermolecular Acylcyanation and Aminocyanation of Alkenes.

Electrocatalytic three-component acylcyanation and aminocyanation of simple alkenes have been developed. The protocol features high functional group tolerance and can easily be scaled up. The key to success is to use an electrophilic cyanation source, enabling a broadened use of alkenes to aliphatic ones for acylcyanation.

A Practically Unified Electrochemical Strategy for Ni-Catalyzed Decarboxylative Cross-Coupling of Aryl Trimethylammonium Salts.

By merging electrocatalysis and nickel catalysis, a unified strategy has been successfully applied to achieve the decarboxylative cross-coupling of four types of α-oxocarboxylic acids and their derivatives with aryl trimethylammonium salts under mild conditions. Our strategy provides a practical way for preparing aryl ketones, amides, esters, or aldehydes.

Electrochemical Oxidative C(sp3)-H/N-H Coupling of Diarylmethanes with Sulfoximines or Benzophenone Imine.

Herein, we report an efficient electrochemical method for the synthesis of N-alkylated sulfoximines by electrochemical oxidative C(sp3)-H/N-H coupling of sulfoximines and diarylmethanes. In addition, we used the same conditions for electrochemical dehydrogenative amination of diarylmethanes with benzophenone imine as an aminating agent. The reactions showed good functional group tolerance and afforded the corresponding products in moderate to good yields without the use of a stoichiometric oxidant, a metal catalyst, or an activating agent.

Electrochemical Oxidative Syntheses of NH-Sulfoximines, NH-Sulfonimidamides and Dibenzothiazines via Anodically Generated Hypervalent Iodine Intermediates.

Herein, we report a general method for the synthesis of NH-sulfoximines and NH-sulfonimidamides through direct electrochemical oxidative catalysis involving an iodoarene(I)/iodoarene(III) redox couple. In addition, dibenzothiazines can be synthesized from [1,1'-biaryl]-2-sulfides under standard conditions. Notably, only a catalytic amount of iodoarene is required for the generation in situ of an active hypervalent iodine catalyst, which avoids the need for an excess of a hypervalent iodine reagent relative to conventional approaches. Moreover, this protocol features broad substrate scope and wide functional group tolerance, delivering the target compounds with good-to-excellent yields even for a scale of more than 10 g.

Electrochemical Oxidative Halogenation of N-Aryl Alkynamides for the Synthesis of Spiro[4.5]trienones.

We developed a green method for the synthesis of spiro[4.5]trienones through an electrochemical oxidative halocyclization with N-aryl alkynamides. This reaction was conducted under metal-catalyst- and exogenous-oxidant-free conditions at room temperature. Using readily available LiCl, LiBr, and LiI as the halogen source, a variety of dearomative halo-spirocyclization products were obtained in good to excellent yields with a broad scope and functional group tolerance.

Electrochemical Tandem Fluoroalkylation-Cyclization of Vinyl Azides: Access to Trifluoroethylated and Difluoroethylated N-Heterocycles.

A transition-metal- and oxidant-free electrochemical strategy for radical fluoroalkylation of vinyl azides was developed. The reaction was carried out under mild conditions by using inexpensive and bench-stable RfSO2Na (Rf = CF3, CF2H) as fluorination reagents. Depending on the starting material, both the electrochemical radical cyclization and dearomatization products could be obtained. This method provides a green and safe approach to synthesize fluorinated nitrogen heterocycles.

Manganese-Catalyzed ortho-C-H Amidation of Weakly Coordinating Aromatic Ketones.

An efficient manganese-catalyzed ortho-C-H amidation of weakly coordinating aromatic ketones using the readily available sulfonyl azide as the amination reagent is developed. The key step is the ketone directed aromatic metalation using the in situ generated reactive Mn intermediate, MnMe(CO)5. This method offers excellent chemical yields, high regioselectivities, and good functional group tolerance.

Hybrid supramolecular materials constructed from pillar[5]arene based host-guest interactions with photo and redox tunable properties.

Monocarboxylate functionalized pillar[5]arene 1 with excellent solubility in organic solvent was prepared. It could be abosorpted on the surface of gold nanorod spontaneously. Then, hybrid supramolecular materials were constructed from 1 stabilized gold nanorods and a linear dinitriles 2 driven by host-guest interaction. Interestingly, the hybrid supramolecular materials show dynamic near-infrared (NIR) and redox dual-responsive reversible properties. 1H nuclear magnetic resonance (NMR) spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical microscopy, and specific viscosity were used to characterize the obtained materials and the reversible behavior under external stimuli. We suggest that this NIR and redox dual-responsiveness properties would be useful in preparation other smart materials and have potential in vivo applications.

Synthesis of fluorinated carbazoles via C-H arylation catalyzed by Pd/Cu bimetal system and their antibacterial activities.

An effective intramolecular C-H arylation reaction catalyzed by a bimetallic catalytic system Pd(OAc)2/CuI for the synthesis of fluorine-substituted carbazoles from corresponding N-phenyl-2-haloaniline derivatives under ligand free conditions is demonstrated. The established method is effective for both N-phenyl-2-bromoaniline and N-phenyl-2-chloroaniline, and requires the low loading of Pd(OAc)2 (0.5 mol%). A series of new fluorinated carbazoles were synthesized in excellent yields using the protocol (>83%, 19 examples) and were fully characterized by (1)H, (13)C and (19)F NMR spectral data, HRMS and elemental analysis. All compounds were evaluated for their antibacterial activities against four bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and methicillin-resistant S. aureus with resistance to gentamicin) by serial dilution technique. All tested compounds showed antibacterial activity against three test strains (S. aureus, B. subtilis and MRSA), and most of these compounds displayed pronounced antimicrobial activities against these three strains with low MIC values ranging from 0.39 to 6.25 µg/mL. Among them, compounds 7 and 14 exhibited potent inhibitory activity better than reference drugs meropenem and streptomycin. Three compounds (2, 4 and 5) showed antibacterial activity against E. coli. with MIC values from 12.5 to 25 µg/mL.