Journal of Fluorine Chemistry最新文献

Novel simple approach was elaborated for the preparation of 3,3-difluoropyrrolidine hydrochloride starting from commercially available technical 2,2-dichlorotrifluoro-1-iodoethane. Its radical addition to ethylene afforded the corresponding iodide that was transformed into the primary amine. The last one was heated with sodium hydrosulfide to form previously unknown 3,3-difluoropyrrolidine-2-thione which was converted into the target product in high yield. The whole transformation does not require the use of toxic, flammable, explosive and hazardous reagents as well as column chromatography purification. Alternative syntheses have been proposed for the intermediate and target compounds.

Small molecule multi-target drugs substituted with fluorine atom/s or fluorine-containing group/s continue to attract considerable interest in medicinal chemistry due to their advantages in the treatment of multifactorial diseases. In this study, fluorine-containing alkyl and benzenesulfonyl chloride building blocks were reacted with 2,4-dihydroxyacetophenone 1a or 2-hydroxy-4-methoxyacetophenone 1b to afford the corresponding sulfonic ester derivatives 2a–f and 2g–j, respectively. Detailed crystallographic characterization was performed on a representative compound from each series. The compounds were evaluated through enzymatic assays in vitro for potential to inhibit biochemical targets linked to type 2 diabetes mellitus. Compound 1a and its 4-(4-fluorophenyl)sulfonyl derivative 2d exhibited strong and significant inhibitory effect in vitro against α-glucosidase (IC₅₀ = 0.97 ± 0.02 μM and 0.81 ± 0.07 μM, respectively) and α-amylase (IC₅₀ = 6.89 ± 0.04 μM and 4.87 ± 0.02 μM, respectively) compared to acarbose (IC₅₀ = 8.60 ± 0.20 μM and 1.96 ± 0.03 μM, respectively). The presence of a 4-fluorophenylsulfonyl moiety resulted in moderate inhibitory activity for 2d (IC₅₀ = 27.05 ± 0.01 μM) against protein tyrosine phosphatase 1 beta (PTP1B) compared to the PTP1B inhibitor, suramin (IC₅₀ = 4.63 ± 0.003 μM). The test compounds exhibited strong to moderate nitric oxide radical scavenging activity in vitro against ascorbic acid (IC₅₀ = 5.53 ± 0.03 μM) with IC₅₀ values in the range 0.05–19.30 μM. Compounds 1a and 2d did not inhibit superoxide dismutase (SOD) activity. Molecular docking revealed the involvement of hydrophobic, hydrophilic and electrostatic interactions with amino acid residues in the active site of the test enzymes.

Polyfluorinated diaminotetraoxacalixarenes and diaminobicyclooxacalixarene were obtained in good yield by reduction of the corresponding dinitrooxacalixarenes with sodium dithionite. Fluorinated tetraoxacalix[4]arenes with nitro and amino groups located in the inner rim of the macrocycle exists in the solution as an equilibrium mixture of two conformers. For diaminotetraoxacalixarenes the conformational equilibrium is shifted towards conformers having a 1,3-alternate structure. The ESI-MS method shows the possibility of complexing fluorinated diaminotetraoxacalixarenes and diaminobicyclooxacalixarenes with metal cations.

Palladium-catalyzed allylic substitution reaction of ethyl tetrafluorocyclopentenyl carbonate or tetrafluorocyclopentenyl methanesulfonate with carbon, nitrogen, and oxygen nucleophiles was systematically investigated. As a result, malonate-derived enolates as a carbon nucleophile, primary and secondary amines as a nitrogen nucleophile, and phenoxide derivatives as an oxygen nucleophile participated all in the reaction very well to furnish the corresponding allylated malonates, allylic amines, and allyl aryl ethers in high yields, respectively. DFT calculations of the reaction mechanism indicate that the direction of nucleophile's attack in the case of carbon nucleophiles, unlike other nucleophiles, is considerably off from the ideal direction, and thus the distance of the newly formed carbon-carbon bond is also considerably longer than the commonly accepted one. It was found then that the activation energies for reactions with carbon nucleophiles were considerably larger than those for reactions with nitrogen or oxygen nucleophiles, and hence the reaction with carbon nucleophiles is less likely proceed.

Deoxygenative perfluoroalkylthiolation reactions of readily available carboxylic acid derivatives have been developed using a series of 2-(perfluoroalkylthio)benzothiazolium (BT-SR_F) reagents as convenient sources of perfluoroalkylthiolate anions. This method avoids pre-activation of the substrates and delivers rarely reported perfluoroalkyl thioesters featuring SR_F groups up to C₆F₁₃. A survey of carboxylic acid substrates with the pentafluoroethylthiolating reagent BT-SC₂F₅ also revealed the generality of the approach as a method for accessing underexplored fluorinated compounds.

An aza-Wittig reaction of in situ generated difluoroalkyl diazo analog, (β-diazo-α,α-difluoroethyl)phosphonates, with aldehyde under mild conditions has been developed to afford difluoromethylphosphonate-containing arylidene hydrazones up to 99 % yields. The reaction was carried out under mild conditions with a broad substrate scope and was suitable for scale-up application. This reaction provides an efficient method for the facile construction of a series of difluoromethylphosphonate-containing arylidene hydrazones and is also a useful supplement to the transformation of (β-diazo-α,α-difluoroethyl)phosphonates.

In this work, we have used a new approach for the synthesis of aryl fluoroglycoside analogues. This strategy used a simple metal-mediated anomeric arylation leading to phenolic fluoroglycosides. Moreover, we determined the rate constants of the acid-catalyzed hydrolysis of original and known mono- and polyfluorinated aryl O- and S-glycosides. For simple phenyl O-fluoroglucosides, the pseudo-first order rate constant for acid-catalyzed hydrolysis was smaller for the β anomer than for the α anomer. As for 4-carboxyphenyl O-galactosides, the rate constant varies as follows: nonfluorinated > 6-deoxy-6-fluoro > 3-deoxy-3-fluoro ≈ 4-deoxy-4-fluoro > 2-deoxy-2-fluoro > polyfluorinated. Finally, we observed a diminution in the hydrolysis rate constant with an increase in the number of integrated fluorine atoms as compared to the native carbohydrate.

Herein, we report an iron-catalyzed sulfur alkylation between sulfenamides and in situ-generated 2,2,2-trifluorodiazoethane to access sulfilimines. This protocol involves the use of inexpensive PcFe as the catalyst. The reaction features operational simplicity, mild conditions and open air, providing a facile approach to trifloromethylated sulfilimines in moderate to good yields.

A catalyst- and solvent-free 1,3-dipolar cycloaddition of a bench-stable diazo reagent, 2-diazo-1,1,3,3,3-pentafluoropropyl phosphonate with selected alkynes is reported. As a result, a series of novel 3H-pyrazoles bearing difluoromethyl phosphonate unit is obtained in moderate-to-excellent yields. This approach provides an efficient and easy route to this valuable class of compounds.

Multigram synthesis of diastereomerically pure cis- and trans-6,6-difluorobicyclo[3.1.0]hexane building blocks starting from commercially available compounds is described. The diastereomeric mixture obtained by reaction of TMSCF₃ – NaI system with non-activated cyclopentene fragment using the slow addition protocol was effectively separated by flash column chromatography. Further simple chemical transformations produced diastereopure amines and carboxylic acids – promising building blocks for drug discovery. Physicochemical properties (i.e., pK_a and LogP) were measured for the title scaffold derivatives and compared with those with monocyclic and non-fluorinated counterparts. Two rigidified analogues of marketed anti-HIV drug Maraviroc were synthesized and evaluated by docking and molecular dynamics studies.