Biarylcarboxylic Acids Research Articles

Synthesis of Biaryl Carboxylic Acids through a Cascade Suzuki-Miyaura Coupling/Friedel-Crafts Alkylation/Lewis-Acid-Catalyzed Rearrangement/Aromatization Process.

In this study, we present a series of 1,3-dicarbonyls that can undergo a cascade Suzuki coupling, followed by a Friedel-Crafts reaction to produce molecules containing polycyclic alcohols. These polycyclic alcohols can then be converted into biaryl carboxylic acids through ring-opening rearrangement reactions catalyzed by a Lewis acid. The Friedel-Crafts reaction exhibits selective para-positioning of the hydroxyl group and demonstrates good compatibility with functional groups with a yield of up to 82%. Substrates with substituted hydroxyl groups can also be converted into biaryl carboxylic acids through a Lewis-acid-catalyzed ring-opening rearrangement.

Electricity-Promoted Friedel-Crafts Acylation of Biarylcarboxylic Acids.

An electricity-promoted method for Friedel-Crafts acylation of biarylcarboxylic acids is described in this research. Various fluorenones can be accessed in up to 99% yields. During the acylation, electricity plays an essential role, which might motivate the chemical equilibrium by consuming the generated TFA. This study is predicted to provide an avenue to realize Friedel-Crafts acylation in a more environmentally friendly process.

Pyrylium salts acting as both energy transfer and electron transfer photocatalysts for E → Z isomerization of activated alkenes and cyclization of cinnamic or biaryl carboxylic acids

Here we report that 2,4,6-triarylpyrylium salts could perform both energy transfer and electron transfer photocatalysis modes for E → Z isomerization of activated alkenes and cyclization of cinnamic or biaryl carboxylic acids.

Direct Deoxygenative Intramolecular Acylation of Biarylcarboxylic Acids

A photocatalyzed intramolecular cyclization is developed for the synthesis of fluorenones. In this photoredox reaction, triphenylphosphine is used as an inexpensive and effective deoxygenative reagent for biarylcarboxylic acids to give acyl radicals, which quickly undergo intramolecular radical cyclization. Reactions in the presence of air and continuous flow photoredox technology demonstrate the generality and practicality of this process.

Exploration of Biaryl Carboxylic Acids as Proton Shuttles for the Selective Functionalization of Indole C-H Bonds.

A survey of diversely substituted 2-arylbenzoic acids were synthesized and tested for use as proton shuttle in the direct arylation of indoles with bromobenzenes. It was found that 3-ethoxy-2-phenylbenzoic acid gives superior yield and selectivity for this class of substrates.

Vitamin Catalysis: Direct, Photocatalytic Synthesis of Benzocoumarins via (-)-Riboflavin-Mediated Electron Transfer.

An operationally simple protocol is disclosed to facilitate entry to benzo-3,4-coumarins directly from biaryl carboxylic acids without the need for substrate prefunctionalization. Complementary to classic lactonization strategies, this disconnection relies on the oxidation competence of photoactivated (-)-riboflavin (vitamin B2) to generate the heterocyclic core via photoinduced single electron transfer. Collectively, the inexpensive nature of the catalyst, ease of execution, and absence of external metal additives are a convincing endorsement for the incorporation of simple vitamins in contemporary catalysis.

Photoredox-Catalyzed Deoxygenative Intramolecular Acylation of Biarylcarboxylic Acids: Access to Fluorenones.

An efficient deoxygenative radical cyclization reaction has been reported for the synthesis of fluorenones by employing various biarylcarboxylic acids via photoredox catalysis. Attractive features of this process include generation of acyl radical, which quickly underdone intramolecular radical cyclization. This method marks the first photocatalytic intramolecular acyl radical coupling for constructing carbon-carbon bond, which further synthesizes the valuable fluorenone products with mild conditions, good yields, and good functional-group compatibility.

ChemInform Abstract: Synthesis of Fluorenones Through Rhodium‐Catalyzed Intramolecular Acylation of Biarylcarboxylic Acids.

AbstractIndependent from the applied method, transformation of the 4‐bromophenyl benzoic acid analogue of (I) proceeds sluggishly furnishing the corresponding product in low or trace amounts.

Intramolecular Acylation of Biarylcarboxylic Acids to Fluorenones

Key words fluorenones - C−H activation - rhodium - intramolecular acylation

Synthesis of fluorenones through rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids.

An efficient approach to the synthesis of fluorenones via the rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids was developed. Using this procedure, fluorenones with various substituents can be synthesized in good to high yields. This work marks the first recorded use of catalytic intramolecular acylation to synthesize fluorenones.

General and Practical Carboxyl‐Group‐Directed Remote CH Oxygenation Reactions of Arenes

Two methods for remote aromatic CH oxygenation reactions, have been developed. Method 1, the Cu-catalyzed oxygenation reaction, is highly efficient for cyclization of electron-neutral and electron-rich biaryl carboxylic acids into 3,4-benzocoumarins. Method 2, the K2S2O8-mediated oxygenation reaction, is more general and practical for cyclization of substrates with electron-donating and -withdrawing groups (see scheme).

Microwave-Assisted Synthesis of Dibenzoazepinones

Reported is a multicomponent ­reaction towards the dibenzo[c,e]azepinone scaffold, starting first via a Suzuki coupling of commercially available 2-formylphenylboronic acids and substituted ortho-bromobenzoates. After ­hydrolysis of the ester, the biaryl carboxylic acids were reacted in a microwave-assisted Ugi reaction. This reaction was optimized for the solvent and temperature, with trifluoroethanol being optimal at 110 ˚C with anhydrous sodium sulfate as additive. The range of substituents studied on the biaryl moiety was not impressive, but the range of dibenzoazepinones synthesized was. The overall yields range from mediocre to good and in one case, the cyclic azepinone was converted into the corresponding thioamide using Lawesson’s reagent.

Solid phase cross-coupling reaction of aryl(halo)silanes with 4-iodobenzoic acid

Aryl(alkyl)(halo)silanes undergo facile and efficient palladium catalyzed cross-coupling reaction with iodobenzoic acid tethered to the Wang resin. Acid cleavage releases unsymmetrical biaryl carboxylic acids with high conversions, purities and yields.

Solid-phase cross-coupling reaction of aryl(fluoro)silanes with 4-iodobenzoic acid

Aryl(alkyl)(difluoro)silanes undergo a facile and efficient palladium-catalyzed cross-coupling reaction with iodobenzoic acid tethered to the Wang resin. Acid cleavage releases unsymmetrical biaryl carboxylic acids with high conversions, purities, and yields.

Fibrinolytic activity of some biarylcarboxylic acids.

BUFFERED solutions of certain aromatic acids dissolve human plasma clots when incubated with them in vitro1,2. The most active in this respect have proved to be arylcarboxylates, which possess an additional free rotating phenyl ring, for example, N-phenylanthranilates3, 5-benzyloxysalicylates4 and diphenylethylacetate5. It was suggested that non-condensed aryl rings in the presence of an acidic functional group are required to render a highly active fibrinolytic agent5.