Palladium-Catalyzed Decarboxylative Annulation Reaction of Aryl Iodides and Methyl 2-Haloarenecarboxylates.

A ligand-free palladium-catalyzed and norbornadiene-mediated annulation reaction of iodoarenes with methyl 2-haloarenecarboxylates is reported. The sequentially accomplished reaction comprises intermolecular C-H arylation, followed by intramolecular decarboxylative annulation, affording various valuable phenanthrenes. This reaction protocol could be expanded to triphenylene syntheses whereby norbornene was the cocatalyst. Interestingly, the decarboxylation of methyl esters was accomplished via solvent-mediated CMe-O bond cleavages.

Synthesis of α-sulfenylated carbonyl compounds under metal-free conditions.

An efficient synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols under heating conditions is described. The method is characterized by mild conditions, simple operation, metal-free catalysis and good functional group tolerance. Mechanistic studies suggest that the reaction involves a radical pathway and an isomerization process.

Synthesis of N-substituted phthalimides via Pd-catalyzed [4+1] cycloaddition reaction.

A novel Pd-catalyzed assembly of N-substituted phthalimides by merging of [4+1] cycloaddition and difluorocarbene transfer carbonylation from 2-iodo-N-phenylbenzamides and difluorocarbene precursors is disclosed. Difluorocarbene acts as a carbonyl source and simultaneously forms one C-C bond, one C-N bond and one CO bond to produce N-substituted phthalimides in high yields.

Copper- and Visible-Light-Catalyzed Cascade Radical Cyclization of N-Propargylindoles with Cyclic Ethers.

An efficient visible-light-assisted, copper-catalyzed tandem radical cyclization of N-propargylindoles with cyclic ethers is established. A series of 2-oxoalkyl-9H-pyrrolo[1,2-a]indol-9-ones with potential biological activities were synthesized in moderate yields by using a dual catalytic system with copper acetate as a transition metal catalyst and eosin Y as a visible light catalyst. The investigation of reaction mechanism shows that it goes through a cascade oxoalkyl radical addition, cyclization, and oxidation process.

TsCl-promoted thiolation of quinoline N-oxides with thiophenols.

A metal-free method for the regioselective synthesis of 2-thiolated quinolines from quinoline N-oxides in water at room temperature is developed. The reaction is conducted using benzenethiols as thiolation reagents in the presence of p-toluenesulfonyl chloride via p-toluenesulfonyl chloride-assisted tandem C-H bond activation, nucleophilic addition, deoxygenation and aromatization processes. This method does not require the use of metal catalysts and oxidants. It shows the advantages of wide functional group tolerance, short reaction times and simple operation.

Synthesis of 10H-indolo[1,2-a]indol-10-ones via palladium-catalyzed C-H bond activation and difluorocarbene transfer.

A Pd-catalyzed annulation between 1-(2-iodophenyl)-1H-indoles and sodium difluorochloroacetate has been developed to synthesize 10H-indolo[1,2-a]indol-10-one derivatives via C-H bond activation and difluorocarbene transfer. Our route enables facile access to the targeted products with various substituents in moderate to high yields. This method features high reactivity, good functional group tolerance, a simple operation procedure, and mild reaction conditions. The reaction can be carried out on a gram scale.

Recent progress in organophotoredox reaction.

In the past decade, visible light photoredox catalysis has been established as a gentle and powerful strategy for the activation of organic molecules. As an important part of this, organic photocatalysts are widely used in chemical synthesis due to their attributes, such as cheapness and relatively high redox potential. In this article, we review the related organic reactions promoted by visible light in the presence of various organic photocatalysts over the past 5 years. The reaction mechanisms involving single electron transfer, energy transfer and proton-coupled electron transfer are also discussed. The recovery and reuse of some supported organic photocatalysts are highlighted. Moreover, prospects for the development of organic photocatalysts are emphasized.

Double C-N bond cleavages of N-alkyl 4-oxopiperidinium salts: access to unsymmetrical tertiary sulfonamides.

In this paper, regiospecific, double intraannular C-N bond cleavages of N-alkyl 4-oxopiperidinium salts are presented. The reaction sequence involves a charge-transfer complex, in situ formed between sulfonyl chloride and N-methylmorpholine, which induces S-Cl bond homolysis of sulfonyl chloride, yielding a reactive sulfonyl radical that further induces the double C-N bond cleavages of N-alkyl 4-oxopiperidinium salt. The secondary amine thus produced was trapped by sulfonyl chloride to yield the desired sulfonamide product. The key feature of this protocol is that two intraannular C-N bonds of the 4-oxopiperidine ring are cleaved in one step under metal- and oxidant-free conditions.

Sulfonylation of 1,4-Diazabicyclo[2.2.2]octane: Charge-Transfer Complex Triggered C-N Bond Cleavage.

A novel charge-transfer complex triggered sulfonylation of 1,4-diazabicyclo[2.2.2]octane (DABCO) with mild reaction conditions has been developed. The formation of a charge-transfer complex between electron-withdrawing (hetero)aryl sulfonyl chloride and DABCO allows the synthesis of N-ethylated piperazine sulfonamide in good yields. The reaction has a high functional group tolerance. Spectroscopic studies confirmed the charge-transfer complex formation between sulfonyl chlorides and DABCO, which facilitates the C-N bond cleavage of DABCO.

Efficient synthesis of aliphatic sulfones by Mg mediated coupling reactions of sulfonyl chlorides and aliphatic halides.

Sulfonyl chlorides were reduced to anhydrous sulfinate salts with magnesium under sonication. These sulfinates were alkylated to sulfones with alkyl chlorides in the presence of catalytic sodium iodide under sonication. A variety of aliphatic sulfones was efficiently prepared by this one-pot two-step procedure.

Magnesium salt promoted tandem nucleophilic addition-Oppenauer oxidation of aldehydes with organozinc reagents.

A magnesium salt promoted synthesis of ketones via tandem nucleophilic addition-Oppenauer oxidation of aldehydes using organozinc chemistry was demonstrated. Magnesium salts concomitantly generated via magnesium metal mediated organohalide zincation exhibit high efficacy for nucleophilic addition of organozinc reagents to aromatic aldehydes and thereafter Oppenauer oxidation whereby ketones are formed in high to excellent yields.

CuI catalyzed sulfonylation of organozinc reagents with sulfonyl halides.

In this study, a facile CuI catalyzed synthesis of sulfones involving a nucleophilic addition of functionalized organozinc reagents to organic sulfonyl chlorides is realized. This reaction proceeds efficiently at room temperature, giving rise to various functional group substituted sulfones, generally in moderate to high yields. The method provides a novel, simple, and promising strategy for functionalized sulfone synthesis in the research field of sulfur chemistry.

4,6-Di-bromo-N-{3-[(4,6-di-bromo-2,3-di-methyl-phenyl)imino]butan-2-yl-idene}-2,3-di-methyl-aniline.

The title compound, C20H20Br4N2, is a product of the condensation reaction of 4,6-di-bromo-2,3-di-methyl-aniline and butane-2,3-dione. The mol-ecule has a center of symmetry at the mid-point of the central C-C bond. The dihedral angle between the benzene ring and the 1,4-di-aza-butadiene plane is 78.3 (2)°. Niether hydrogen bonding nor aromatic stacking is observed in the crystal structure.

2-[(5'-Chloro-1,1':3',1''-terphenyl-4'-yl)imino]-acenaphthylen-1(2H)-one.

The title compound, C30H18ClNO, is a product of the condensation reaction of acenaphthyl-ene-1,2-dione and 5'-chloro-1,1':3',1''-terphenyl-4'-amine. The acenaphthyl-ene fragment and two terminal phenyl rings are rotated relative to the central benzene ring by 72.2 (3), 43.2 (3) and 41.2 (3)°, respectively. This mol-ecular conformation is supported by weak C-H⋯π inter-actions. In the crystal, mol-ecules form centrosymmetric dimers by the stacking inter-actions between two neighboring acenaphthyl-ene fragments, with an inter-planar distance of 3.365 (3) Å. The dimers are bound to each other by weak C-H⋯N and C-H⋯π inter-actions, forming a three-dimensional framework.

Tandem nucleophilic addition-Oppenauer oxidation of aromatic aldehydes to aryl ketones with triorganoaluminium reagents.

In the presence of pinacolone, the in situ prepared triorganoaluminium reagents reacted with aromatic aldehydes to give ketones in moderate to high yield. We propose that the products are formed via a tandem organoaluminium reagents addition-Oppenauer oxidation sequence.

Rhodium(III)-catalyzed oxidative mono- and di-olefination of isonicotinamides.

[RhCp*Cl(2)](2) can catalyze the oxidative coupling of secondary isonicotinamides with activated olefins using Cu(OAc)(2) as an oxidant. The selectivity can be controlled by the solvent. In MeCN, the mono-olefination and two-fold oxidation reaction is the major pathway, while in THF this reaction gave mostly diolefination products. In both cases, the coupled products contain an exocyclic C=C bond.

Synthesis of 1-aminoisoquinolines via Rh(III)-catalyzed oxidative coupling.

[RhCp*Cl(2)](2) can catalyze the oxidative coupling of N-aryl and N-alkyl benzamidines with alkynes to give N-substituted 1-aminoisoquinolines in high selectivity.

Oxidative coupling of NH isoquinolones with olefins catalyzed by Rh(III).

Rh(III)-catalyzed oxidative coupling reactions between isoquinolones with 3-aryl groups and activated olefins have been achieved using anhydrous Cu(OAc)(2) as an oxidant to give tetracyclic products. The nitrogen atom acts as a directing group to facilitate ortho C-H activation. This reaction can be one-pot starting from methyl benzohydroxamates, without the necessity of the isolation of isoquinolone products. A broad scope of substrates has been demonstrated, and both terminal and internal activated olefins can be applied. In the coupling of N-methylmaleimide, a Wacker-like mechanism was proposed, where backside attack of the NH group in isoquinolones is suggested as a key step. Selective C-H activation has also been achieved at the 8-position of 1-naphthol, leading to an olefination product.

Investigation of physicochemical properties of lactam-based Brønsted acidic ionic liquids.

Novel lactam-cation-based Brønsted acid ionic liquids (ILs) were prepared through a simple and atom-economic neutralization reaction between a lactam, such as caprolactam and butyrolactam, and a Brønsted acid, HX, where X is BF4-, CF3COO-, phCOO-, ClCH2COO-, NO3-, or H2PO4-. The density, viscosity, acidic scale, electrochemical window, temperature dependency of ionic conductivity, and thermal property of these ILs were measured and investigated in detail. The results show that protonated caprolactam tetrafluoroborate (CPBF) has a relatively strong acidity with -0.22 of Hammett acidic scale H0 and caprolactam trifluoroacetate (CPTFA) and pyrrolidonium trifluoroacetate (PYTFA) ILs possess very low viscosities, that is, 28 cP and 11 cP, respectively. An investigation of thermal property showed that a wide liquid range (up to -90 degrees C), moderate thermal stability (up to 249 degrees C for 10% of decomposition), and complex polymorphism were observed in these ILs. In comparison to imidazolium-cation-based ILs, the lactam-cation-based Brønsted acid ILs have a relatively lower cost, lower toxicity, and comparable ion conductivity and heat storage density (more than 200 MJ/m3). They have wide applicable perspectives for fuel cell devices, thermal transfer fluids, and acid-catalyzed reaction media and catalysts as replacements of conventional inorganic acids.