An eccentric rod-like linear connection of two heterocycles: synthesis of pyridine trans-tetrafluoro-λ6-sulfanyl triazoles

TBHP Promotes Cross-Dehydrogenative Coupling of SF4 Alkynes with Tetrahydroisoquinolines under Copper Catalysis

We present a viable approach for the cross-dehydrogenative coupling of Het-SF4-alkynes with tetrahydroisoquinolines under oxidative conditions, using TBHP and copper catalysts. These newly developed conditions boast enhanced yields and a more extensive range of substrates, demonstrating tolerance to various functional groups and addressing the limitations of earlier reports. Consequently, this method should increase opportunities for the exploration of SF4-containing compounds and their potential applications in drug discovery, materials science, and as alternatives to PFAS.

Overcoming a Radical Polarity Mismatch in Strain-Release Pentafluorosulfanylation of [1.1.0]Bicyclobutanes: An Entryway to Sulfone- and Carbonyl-Containing SF5-Cyclobutanes

The first assortment of achiral pentafluorosulfanylated cyclobutanes (SF5-CBs) are now synthetically accessible through strain-release functionalization of [1.1.0]bicyclobutanes (BCBs) using SF5Cl. Methods for both chloropentafluorosulfanylation and hydropentafluorosulfanylation of sulfone-based BCBs are detailed herein, as well as proof-of-concept that the logic extends to tetrafluoro(aryl)sulfanylation, tetrafluoro(trifluoromethyl)sulfanylation, and three-component pentafluorosulfanylation reactions. The methods presented enable isolation of both syn and anti isomers of SF5-CBs, but we also demonstrate that this innate selectivity can be overridden in chloropentafluorosulfanylation; that is, an anti-stereoselective variant of SF5Cl addition across sulfone-based BCBs can be achieved by using inexpensive copper salt additives. Considering the SF5 group and CBs have been employed individually as nonclassical bioisosteres, structural aspects of these unique SF5-CB "hybrid isosteres" were then contextualized using SC-XRD. From a mechanistic standpoint, chloropentafluorosulfanylation ostensibly proceeds through a curious polarity mismatch addition of electrophilic SF5 radicals to the electrophilic sites of the BCBs. Upon examining carbonyl-containing BCBs, we also observed rare instances whereby radical addition to the 1-position of a BCB occurs. The nature of the key C(sp3)-SF5 bond formation step - among other mechanistic features of the methods we disclose - was investigated experimentally and with DFT calculations. Lastly, we demonstrate compatibility of SF5-CBs with various downstream functionalizations.

Transition-Metal-Free Approach for Z-Vinyl Fluorides by Hydrofluorination of Alkynes bearing SF4 and SF5 Groups

The synthesis of vinyl fluorides plays a crucial role in various scientific disciplines, including pharmaceutical and materials sciences. Herein, we present a direct and stereoselective hydrofluorination method for the synthesis of Z isomers of vinyl fluorides from alkynes containing unexplored SF5 and SF4 groups. Our strategy employed tetrabutylammonium fluoride (TBAF) as a fluorine source. It demonstrates high compatibility with aryls, biaryls, heteroaryls, and tert-alkyl groups, allowing facile incorporation of SF5 and SF4 groups across the triple bond without any transition-metal catalysts. This approach avoids the potential decomposition of the SF5 or SF4 units via coordination with transition metals or acidic protic sources. Remarkably, this transformation proceeded at room temperature without any additional additives, providing the Z isomer of vinyl fluorides in excellent yield and high selectivity. The presence of a water molecule as a hydrate in TBAF is essential for efficient conversion. This methodology opens new avenues for the synthesis of enchanting SF5 - and SF4 -containing fluorinated vinylic scaffolds, thereby providing advanced opportunities for novel drug discovery and fluorinated polymers.

Expanding the Frontier of Linear Drug Design: Cu-Catalyzed Csp -Csp 3 -Coupling of Electron-Deficient SF4 -Alkynes with Alkyl Iodides

Despite the attractive properties of tetrafluorosulfanyl (SF4 ) compounds in drug discovery, medicinal research on SF4 molecules is hindered by the scarcity of suitable synthetic methodologies. Drawing inspiration from the well-established Sonogashira cross-coupling of terminal alkynes under Pd-catalysis, it is envisioned that SF4 -alkynes can serve as effective coupling partners. To overcome the challenges associated with the electron-deficient nature of SF4 -alkynes and the lability of the SF4 unit under transition-metal catalysis, an aryl radical mediated Csp -Csp 3 cross-coupling reaction is successfully developed under Cu catalysis. This methodology facilitates the coupling of SF4 -alkynes with alkyl iodides, leading to the immediate synthesis of SF4 -attached drug-like molecules. These findings highlight the potential impact of SF4 -containing molecules in the drug industry, paving the way for further research in this emerging field.

Cross Dehydrogenative Coupling of SF4-Alkyne with Tetrahydroisoquinolines

This study introduces a dual-catalytic method for cross-dehydrogenative coupling (CDC) between tetrahydroisoquinolines and Py-SF4-alkyne using visible-light photoredox catalysis. This protocol enables selective C(sp3)-H alkynylation, expanding the synthetic toolkit for SF4-based molecules. Demonstrating efficiency and substrate versatility, this approach opens new avenues in hexacoordinated tetrafluorinated sulfur chemistry and CDC strategies and holds significant promise for drug discovery and materials science.

Strain-Release Pentafluorosulfanylation and Tetrafluoro(aryl)sulfanylation of [1.1.1]Propellane: Reactivity and Structural Insight

We leveraged the recent increase in synthetic accessibility of SF5 Cl and Ar-SF4 Cl compounds to combine chemistry of the SF5 and SF4 Ar groups with strain-release functionalization. By effectively adding SF5 and SF4 Ar radicals across [1.1.1]propellane, we accessed structurally unique bicyclopentanes, bearing two distinct elements of bioisosterism. Upon evaluating these "hybrid isostere" motifs in the solid state, we measured exceptionally short transannular distances; in one case, the distance rivals the shortest nonbonding C⋅⋅⋅C contact reported to date. This prompted SC-XRD and DFT analyses that support the notion that a donor-acceptor interaction involving the "wing" C-C bonds is playing an important role in stabilization. Thus, these heretofore unknown structures expand the palette for highly coveted three-dimensional fluorinated building blocks and provide insight to a more general effect observed in bicyclopentanes.

(Hetero)aryl-SVI Fluorides: Synthetic Development and Opportunities

(Hetero)arylsulfur compounds where the S atom is in the oxidation state VI represent a large percentage of the molecular functionalities present in organic chemistry. More specifically, (hetero)aryl-SVI fluorides have recently received enormous attention because of their potential as chemical biology probes, as a result of their reactivity in a simple, modular, and efficient manner. Whereas the synthesis and application of the level 1 fluorination at SVI atoms (sulfonyl and sulfonimidoyl fluorides) have been widely studied and reviewed, the synthetic strategies towards higher levels of fluorination (levels 2 to 5) are somewhat more limited. This Minireview evaluates and summarizes the progress in the synthesis of highly fluorinated aryl-SVI compounds at all levels, discussing synthetic strategies, reactivity, the advantages and disadvantages of the synthetic procedures, the proposed mechanisms, and the potential upcoming opportunities.

Synthesis of Pyridine-SF4-Isoxazolines Using the Functionality of trans-Tetrafluoro-λ6-sulfanyl Rodlike Linkers

The tetrafluoro-λ⁶-sulfanyl (SF₄) moiety has been relatively undeveloped since its discovery in the 1970s. In this study, we synthesized pyridine-SF₄-isoxazolines, in which the two heterocycles are connected by a rodlike trans-SF₄ linker, via the regioselective 1,3-dipolar cycloaddition of pyridine-SF₄-alkynes and nitrones in the presence of triethylamine. SF₄ linkers are a viable alternative to para-substituted benzenes, alkynes, and bicyclo[1.1.1]pentyl derivatives in drug design, and pyridine-SF₄-isoxazolines have potential applications in drug development.

Regioselective Synthesis of Pyridine-SF4-Methyl Ketones via Hydration of Pyridine-SF4-Alkynes

Herein, we report the metal-free hydration of pyridine-SF₄-alkynes, under acidic conditions and with reaction durations ranging from 5 min to 10 h at room temperature, to synthesize pyridine-SF₄-methyl ketones in yields of 59-93%. Further, we demonstrate the synthetic applications of the synthesized pyridine-SF₄-methyl ketones, such as chlorination, NaBH₄ reduction, Baeyer-Villiger oxidation, and the generation of enol-triflates. These compounds hold promise as useful building blocks in the syntheses of a wide range of SF₄-containing drug candidates.

Ethynyl-SF4-Pyridines: Reagents for SF4-Alkynylation to Carbonyl Compounds

The trans-tetrafluoro-λ⁶-sulfanyl (SF₄) unit is medicinally attractive because of its high electronegativity, lipophilicity, and unique hypervalent structure. The trans-SF₄ unit can characteristically connect two independent molecules linearly. However, there is no example of the use of this unit for medicinal chemistry due to difficulties in synthesis. We report the first synthesis of (ethynyl-trans-tetrafluoro-λ⁶-sulfanyl)pyridines (t-ethynyl-SF₄-pyridines) and their use as versatile reagents for the first direct SF₄-alkynylation to carbonyl compounds. The addition reaction of t-ethynyl-SF₄-pyridines to the carbonyl group in the presence of MeLi smoothly afforded pyridine-SF₄-propargylic tertiary and secondary alcohols in high yields.

Synthesis of an Eccentric Electron-Deficient Fluorinated Motif, Tetrafluoro-λ6-sulfanyl gem-Difluorocyclopropenes

Fluoro-functionalization is now recognized as a critical strategy in drug discovery; however, the accessible fluoro-functional groups are limited. We herein introduce an eccentric, fully fluorinated motif, trans-tetrafluoro-λ⁶-sulfanyl gem-difluorocyclopropene 2. This novel motif is highly lipophilic and polarized, enabling a connection of two independent groups via three continuous atoms with a large angle of pseudo cis configuration. The target motif was synthesized via a [2+1] cycloaddition of electron-deficient (hetero)aryl-SF₄-alkynes 1 with an electrophilic difluorocarbene source.

Design and Synthesis of an Aniline Derivative with Biological Activity on Heart Failure

BACKGROUND

Several compounds have been synthesized as a therapeutic alternative for heart failure; however, its preparation requires special conditions.

OBJECTIVE

The aim of this study, was to synthesize some aniline derivatives (4-9) from 3- ethynylaniline to evaluate their biological activity against heart failure.

METHODS

The synthesis of aniline derivatives involved a series of reactions such as etherification, addition, and cyclization. The structure of all compounds obtained was confirmed by spectroscopic and spectrometric methods. In addition, to evaluate the biological activity of compounds, an ischemia/reperfusion injury model was used.

RESULTS

The results showed that compound 8 decreases heart failure, which translates into a decrease in the infarction area compared to compounds 4-7 and 9.

CONCLUSION

This study reports a facile method for the preparation of aniline derivatives. This method offers some advantages such as; a simple procedure, low cost, and easy work up. In addition, compound 8 showed an interesting biological activity against heart failure. This phenomenon is particularly interesting because the biological activity induced by this compound could involve a molecular mechanism that is different from other drugs used for the treatment of heart failure.

Pyridine tetrafluoro-λ6-sulfanyl chlorides: spontaneous addition to alkynes and alkenes in the presence or absence of photo-irradiation

A radical addition reaction of Py-SF₄Cl to alkynes and alkenes provide pyridine-SF₄-alkenes and pyridine-SF₄-alkanes under blue LED light irradiation or absence of light irradiation in CPME or without solvent.

Studies of Halogen Bonding Induced by Pentafluorosulfanyl Aryl Iodides: A Potential Group of Halogen Bond Donors in a Rational Drug Design

The activation of halogen bonding by the substitution of the pentafluoro-λ⁶-sulfanyl (SF₅) group was studied using a series of SF₅-substituted iodobenzenes. The simulated electrostatic potential values of SF₅-substituted iodobenzenes, the ab initio molecular orbital calculations of intermolecular interactions of SF₅-substituted iodobenzenes with pyridine, and the ¹³C-NMR titration experiments of SF₅-substituted iodobenzenes in the presence of pyridine or tetra (n-butyl) ammonium chloride (TBAC) indicated the obvious activation of halogen bonding, although this was highly dependent on the position of SF₅-substitution on the benzene ring. It was found that 3,5-bis-SF₅-iodobenzene was the most effective halogen bond donor, followed by o-SF₅-substituted iodobenzene, while the m- and p-SF₅ substitutions did not activate the halogen bonding of iodobenzenes. The similar ortho-effect was also confirmed by studies using a series of nitro (NO₂)-substituted iodobenzenes. These observations are in good agreement with the corresponding Mulliken charge of iodine. The 2:1 halogen bonding complex of 3,5-bis-SF₅-iodobenzene and 1,4-diazabicyclo[2.2.2]octane (DABCO) was also confirmed. Since SF₅-containing compounds have emerged as promising novel pharmaceutical and agrochemical candidates, the 3,5-bis-SF₅-iodobenzene unit may be an attractive fragment of rational drug design capable of halogen bonding with biomolecules.