Rapid F- and F-Difluoromethylation through Desulfurative Fluorination of Transient N-, O-, and C-Linked Dithioles.

The difluoromethyl group plays an important role in modern medicinal and agrochemistry. While several difluoromethylation reagents have been reported, these typically rely on difluoromethyl carbenes or anions, or target specific processes. Here, we describe a conceptually unique and general process for O-H, N-H and C-H difluoromethylation that involves the formation of a transient dithiole followed by facile desulfurative fluorination using silver(I) fluoride.

Perfluoropyridine: Discovery, Chemistry, and Applications in Polymers and Material Science.

Perfluoropyridine (PFPy) is an organofluorine compound that has been employed for a variety of applications, from straightforward chemical synthesis to more advanced functions, such as fluorinated networks and polymers. This can be directly attributed to the highly reactive nature of PFPy, especially towards nucleophilic aromatic substitution (SNAr). The aim of this review is to highlight the discovery and synthesis of PFPy, discuss its reactive nature towards SNAr, and to summarize known reports of the utilization and thermal analysis of PFPy containing fluoropolymers and fluorinated network materials.

Novel perfluoropolyalkylethers monomers: synthesis and photo-induced cationic polymerization.

Unlabelled: Several difunctional oligomers were synthesized by functionalizing perfluoropolyalkylether (PFPAE) chains with different vinyl ethers and epoxides end-groups. Due to their innate synthetic challenges and demanding purification protocols, the PFPAE derivatives were obtained in low yield and with an average functionality lower than 2. However, the functionalized PFPAE oligomers were successful in being used in photo-induced cationic polymerization processes, obtaining transparent and soft films.

Vinyl ethers and epoxides photoinduced copolymerization with perfluoropolyalkylether monomers.

New perfluoropolyalkylether (PFPAE) monomers, chain extended with different alkyl groups and functionalized with vinyl ether or epoxide end-groups, were employed, together with trimethylolpropane trivinyl ether or trimethylolpropane triglycidyl ether, to produce fluorinated copolymers. The photoinduced cationic polymerization was investigated, and the PFPAE-based copolymer properties were thoroughly characterized. Interesting surface properties and two different values of refractive index were observed: thus, these fluorinated copolymers can be suitable materials for the manufacture of self-cleaning coatings and optical waveguides.

Fluorodesulfurization of Thionobenzodioxoles with Silver(I) Fluoride.

Difluorobenzodioxole is an important functional group found in both pharmaceuticals and agrochemicals. The late-stage introduction of this functional group is challenged by typical fluorination conditions of HF and strong oxidants. Here, we demonstrate that a range of difluorobenzodioxoles can be prepared from catechols in two steps through conversion into thionobenzodioxoles, followed by desulfurative fluorination with silver(I) fluoride.

Correction: Synthesis of α,β-unsaturated esters of perfluoropolyalkylethers (PFPAEs) based on hexafluoropropylene oxide units for photopolymerization.

[This corrects the article DOI: 10.1039/C8RA06354K.].

Quaternary Ammonium Trifluoromethoxide Salts as Stable Sources of Nucleophilic OCF.

The reaction of nucleophilic tertiary amines with trifluoromethyl and pentafluoroethyl methyl ethers provides quaternary ammonium trifluoromethoxide (NROCF) and pentafluoroethoxide (NROCFCF) salts, respectively, in good yields. The new trifluoromethoxide salts disclosed herein are uniquely stable for extended periods of time in both the solid state and in solution, which complements contemporary reagents. Here we describe the preparation of a range of NROCF salts, their long-term stability, and utility in substitution reactions.

A Convenient Synthesis of Difluoroalkyl Ethers from Thionoesters Using Silver(I) Fluoride.

Herein we report the mild and rapid fluorodesulfurization of thionoesters using only silver(I) fluoride. This reaction demonstrates excellent functional group tolerance and complements existing strategies for difluoroalkyl ether synthesis, which rely on toxic and often dangerous reagents that demonstrate limited functional group compatibility. We additionally report the translation of this finding to the production of F-labelled difluoroalkyl ethers using fluoride-derived [ F]AgF.

Synthesis of α,β-unsaturated esters of perfluoropolyalkylethers (PFPAEs) based on hexafluoropropylene oxide units for photopolymerization.

α,β-unsaturated esters are usually synthesized for polymer applications. However, the addition of maleate (configuration) to a fluorinated moiety is challenging due to its potential isomerization during esterification. Various synthetic routes were attempted and led to very low conversion or side-products.

Base-Catalyzed Transesterification of Thionoesters.

Here we report a convenient synthesis of thionoesters by base-catalyzed transesterification. Benzyl and alkyl thionobenzoates and thionoheterobenzoates were efficiently prepared using various alcohols catalyzed by the corresponding sodium alkoxide. This methodology features a broad substrate scope, good to excellent yields, short reaction times, while simultaneously driving the reaction toward completion through the removal of the methanol byproduct.

Synthetic access to an elusive high-temperature perfluoroisopropenyl ether prepolymer for radical copolymerization.

A perfluoroisopropenyl ether terminated oligo(hexafluoropropylene oxide), a perfluoropolyalkyl ether macromonomer for radical copolymerization, has been prepared. The synthesis was achieved through a carefully controlled defluorination of a highly unstable lithium perfluorocarbanion intermediate. Several undesired pathways were also observed by GC/MS and we report conditions for generating the desired product in 82% yield.

Direct heterobenzylic fluorination, difluorination and trifluoromethylthiolation with dibenzenesulfonamide derivatives.

Functionalization of heterocyclic scaffolds with mono- or difluoroalkyl groups provides unique opportunities to modulate drug p, influence potency and membrane permeability, and attenuate metabolism. While advances in the addition of fluoroalkyl radicals to heterocycles have been made, direct C(sp)-H heterobenzylic fluorination is comparatively unexplored. Here we demonstrate both mono- and difluorination of a range of alkyl heterocycles using a convenient process that relies on transient sulfonylation by the electrophilic fluorinating agent -fluorobenzenesulfonimide.

A convenient route to tetraalkylammonium perfluoroalkoxides from hydrofluoroethers.

Hydrofluoroethers are shown to alkylate tertiary amines readily under solvent-free conditions, affording valuable tetraalkylammonium perfluoroalkoxides bearing α-fluorines. The reaction of R(F)CF2-OCH3 (R(F)=CF2CF3, CF2CF2CF3, and CF(CF3)2) with NR(1)R(2)R(3) produces twenty new α-perfluoroalkoxides, [(CH3)NR(1)R(2)R(3)][R(F)CF2O] under mild conditions. These α-perfluoroalkoxides are easy to handle, thermally stable, and can be used for the perfluoroalkoxylation of benzyl bromides.

Design and formulation of nanoemulsions using 2-(poly(hexafluoropropylene oxide)) perfluoropropyl benzene in combination with linear perfluoro(polyethylene glycol dimethyl ether).

This is the first report where PFPAE aromatic conjugates and perfluoro(polyethylene glycol dimethyl ether) are combined and formulated as nanoemulsions with droplet size below 100 nm. A perfluoropolyalkylether (PFPAE) aromatic conjugate, 2-(poly(hexafluoropropylene oxide)) perfluoropropyl benzene, was used as fluorophilic-hydrophilic diblock (FLD) aimed at stabilizing perfluoro(polyethylene glycol dimethyl ether) nanoemulsions. Its effects on colloidal behaviors in triphasic (organic/fluorous/aqueous) nanoemulsions were studied.