Deoxyfluorination Reaction Research Articles

Deoxyfluorination: A Detailed Overview of Recent Developments

AbstractFluorine organic compounds have been a predominant force of pharmaceutical chemistry for modern drug design, with an increasing amount of fluorine-containing compounds entering the market. Methodologies for fluorine atom incorporation into organic molecules are still challenging to date and thus represent an important research area. Deoxyfluorination serves as a useful tool for the construction of carbon–fluorine bonds in biologically active molecules by converting a common hydroxyl group into the corresponding fluoride. In this review, we have summarized and categorized deoxyfluorination reaction protocols developed over the last decade (2015–2024) by the structural type of C–O bond deoxyfluorination, including substrates like alcohols, phenols, ketones, aldehydes, and carboxylic acids.1 Introduction2 Deoxyfluorination of C(sp3)–O Bonds2.1 Alcohols2.2 Alcohol Derivatives3 Deoxyfluorination of C(sp2)–O Bonds3.1 Phenols3.2 Phenol Derivatives3.3 Aldehydes and Ketones3.4 Carboxylic Acids4 Conclusions

Phosphonium SF5 - Salts Derived from Sulfur Hexafluoride as Deoxyfluorination Reagents.

Sulfur based deoxyfluorination reagents are usually derived from the corrosive gas SF4. Herein, we report the synthesis and properties of an easily accessible phosphonium salt [(tmg)3PF]+SF5 - (1) which was obtained from the reaction of sulfur hexafluoride (SF6) with tris(tetramethylguanidinyl)phosphine. The performance of this crystalline SF5 - salt as a reagent in deoxyfluorination reactions was investigated together with a second SF5 - salt [(R1)3PF]+SF5 - (2) containing bulky substituents (R1=1,3-di-tert-butylimidazolidin-2-ylidenamino). Both reagents proved to be effective for the deoxyfluorination of various functional groups including alcohols, anhydrides, and amides.

A 2,2-Difluoroimidazolidine Derivative for Deoxyfluorination Reactions: Mechanistic Insights by Experimental and Computational Studies.

A N-heterocyclic deoxyfluorinating agent SIMesF2 was synthesized by nucleophilic fluorination of N,N-1,3-dimesityl-2-chloroimidazolidinium chloride (3) at room temperature. SIMesF2 was applied to deoxyfluorinate carboxylic acids and alcohols and convert benzaldehyde into difluorotoluene. Mechanistic studies by NMR spectroscopy suggest reaction pathways of the carboxylic acid to acyl fluoride via outer-sphere fluorinations at an imidazolidinium ion by polyfluoride. DFT studies give further insight by exploring mechanistic details which distinguish the fluorination of aldehydes from that of carboxylic acids. Furthermore, a consecutive reaction sequence for the oxidation of an aldehyde followed by in situ fluorination of the generated carboxylic acid was developed.

Elemental Sulfur-Mediated Transformation of Carboxylic Acids to Acyl Fluorides by Electrophilic Fluorinating Reagent, Selectfluor.

The elemental sulfur-mediated synthesis of acyl fluorides from carboxylic acids is achieved using Selectfluor. A broad range of acyl fluorides are accessible from carboxylic acids while avoiding the formation of acid anhydrides. 19F NMR spectra suggest that S8-fluoro-sulfonium cation A and neutral S8-difluoride A' generated in situ are the reactive species in this deoxyfluorination reaction.

A Fruitful Decade of Organofluorine Chemistry: New Reagents and Reactions

A Fruitful Decade of Organofluorine Chemistry: New Reagents and Reactions

TMSCF2Br‐Enabled Fluorination–Aminocarbonylation of Aldehydes: Modular Access to α‐Fluoroamides

AbstractA protocol for the modular assembly of the α‐fluoroamide motif has been developed, which provides a practical method for the efficient synthesis of structurally diverse α‐fluoroamides from easily available aldehydes and tertiary amines through a three‐component fluorination–aminocarbonylation process. The key to the success of this process is taking advantage of the multiple roles of the unique difluorocarbene reagent TMSCF2Br (TMS=trimethylsilyl). The mechanism of the process involves the 1,2‐fluorine and oxygen migrations of the in situ formed TMS‐protected α‐aminodifluoromethyl carbinol intermediates, which represents a new type of deoxyfluorination reaction.

TMSCF2 Br-Enabled Fluorination-Aminocarbonylation of Aldehydes: Modular Access to α-Fluoroamides.

A protocol for the modular assembly of the α-fluoroamide motif has been developed, which provides a practical method for the efficient synthesis of structurally diverse α-fluoroamides from easily available aldehydes and tertiary amines through a three-component fluorination-aminocarbonylation process. The key to the success of this process is taking advantage of the multiple roles of the unique difluorocarbene reagent TMSCF2 Br (TMS=trimethylsilyl). The mechanism of the process involves the 1,2-fluorine and oxygen migrations of the in situ formed TMS-protected α-aminodifluoromethyl carbinol intermediates, which represents a new type of deoxyfluorination reaction.

Manufacturing Process Development for Belzutifan, Part 6: Ensuring Scalability for a Deoxyfluorination Reaction

The development of a regio- and stereoselective deoxyfluorination process for the manufacture of belzutifan (MK-6482) was challenging because of a combination of particular reaction and engineering sensitivities. These aspects were addressed through a series of mechanistic, range-finding, and mixing studies that enabled a robust process to be established. In particular, mixing studies led to the discovery of a second phase of perfluoro-1-butanesulfonyl fluoride in the reaction at cryogenic temperature, requiring the liquid–liquid dispersion to be controlled sufficiently to minimize the formation of side products. The changes implemented as a result of these investigations culminated in a process executed successfully on the pilot and commercial scales.

Stereoselective Synthesis of 24-Fluoro-25-Hydroxyvitamin D3 Analogues and Their Stability to hCYP24A1-Dependent Catabolism.

Two 24-fluoro-25-hydroxyvitamin D3 analogues (3,4) were synthesized in a convergent manner. The introduction of a stereocenter to the vitamin D3 side-chain C24 position was achieved via Sharpless dihydroxylation, and a deoxyfluorination reaction was utilized for the fluorination step. Comparison between (24R)- and (24S)-24-fluoro-25-hydroxyvitamin D3 revealed that the C24-R-configuration isomer 4 was more resistant to CYP24A1-dependent metabolism than its 24S-isomer 3. The new synthetic route of the CYP24A1 main metabolite (24R)-24,25-dihydroxyvitamin D3 (6) and its 24S-isomer (5) was also studied using synthetic intermediates (30,31) in parallel.

Deoxyfluorination of Carboxylic Acids with KF and Highly Electron-Deficient Fluoroarenes

A deoxyfluorination reaction of carboxylic acids using potassium fluoride (KF) and highly electron-deficient fluoroarenes is reported here, giving acyl fluorides in moderate to excellent yield (57-92% based on NMR integration and 34-95% for isolated examples).

Bayesian reaction optimization as a tool for chemical synthesis.

Reaction optimization is fundamental to synthetic chemistry, from optimizing the yield of industrial processes to selecting conditions for the preparation of medicinal candidates1. Likewise, parameter optimization is omnipresent in artificial intelligence, from tuning virtual personal assistants to training social media and product recommendation systems2. Owing to the high cost associated with carrying out experiments, scientists in both areas set numerous (hyper)parameter values by evaluating only a small subset of the possible configurations. Bayesian optimization, an iterative response surface-based global optimization algorithm, has demonstrated exceptional performance in the tuning of machine learning models3. Bayesian optimization has also been recently applied in chemistry4-9; however, its application and assessment for reaction optimization in synthetic chemistry has not been investigated. Here we report the development of a framework for Bayesian reaction optimization and an open-source software tool that allows chemists to easily integrate state-of-the-art optimization algorithms into their everyday laboratory practices. We collect a large benchmark dataset for a palladium-catalysed direct arylation reaction, perform a systematic study of Bayesian optimization compared to human decision-making in reaction optimization, and apply Bayesian optimization to two real-world optimization efforts (Mitsunobu and deoxyfluorination reactions). Benchmarking is accomplished via an online game that links the decisions made by expert chemists and engineers to real experiments run in the laboratory. Our findings demonstrate that Bayesian optimizationoutperforms human decisionmaking in both average optimization efficiency (number of experiments) and consistency (variance of outcome against initially available data). Overall, our studies suggest that adopting Bayesian optimization methods into everyday laboratory practices could facilitate more efficient synthesis of functional chemicals by enabling better-informed, data-driven decisions about which experiments to run.

Achievements in fluorination using variable reagents through a deoxyfluorination reaction

The application of fluorination reagent for the direct conversion of alcohols and phenols to fluorinated analogues.

Synthesis and CYP24A1-Dependent Metabolism of 23-Fluorinated Vitamin D3 Analogues.

Two novel 23-fluorinated 25-hydroxyvitamin D3 analogues were synthesized using Inhoffen–Lythgoe diol as a precursor of the CD-ring, efficiently. Introduction of the C23 fluoro group was achieved by the deoxy-fluorination reaction using N,N-diethylaminosulfur trifluoride or 2-pyridinesulfonyl fluoride (PyFluor). Kinetic studies on the CYP24A1-dependent metabolism of these two analogues revealed that (23S)-23-fluoro-25-hydroxyvitamin D3 was more resistant to CYP24A1-dependent metabolism than its 23R isomer.

Tailoring of Energy Band Gap inGraphene-like System by Fluorination

Fluorinated grapheme has a two-dimensional layer structure with a wide band gap. In the present study, Fluoro Graphene (FG) is obtained from Graphene Oxide (GO) through a deoxyfluorination reaction with the aid of Diethylaminosulphurtrifluoride (DAST). The FT-IR exhibited a peak at 1216 cm-1 and the shoulder at 1312 cm-1 were ascribed to the stretching vibration of covalent C–F bonds and C–F2 bonds, respectively. Surface morphology revealed a leafy structure in GO and a rocky structure in FG. The EDS analysis confirmed the fluorination of the graphitic structure. The TEM analysis confirmed the formation of a mixed structure of graphene and carbon dots. The results of structural, morphological and electrical properties of both graphene oxide and fluorographene show the possibility of using these samples as electronic/electrochemical devices in future.

Radical Deoxychlorination of Cesium Oxalates for the Synthesis of Alkyl Chlorides.

A radical deoxychlorination of cesium oxalates has been developed for the preparation of hindered secondary and tertiary alkyl chlorides. The reaction tolerates a number of functional groups, including ketones, alcohols, and amides, and provides complementary reactivity to standard deoxychlorination reactions proceeding by heterolytic mechanisms. Preliminary studies demonstrate that the developed conditions can also be applied to deoxybromination and deoxyfluorination reactions.

Evolution of a Scale-Up Synthesis to a Potent GluN2B Inhibitor and Its Prodrug

This paper describes the efficient scale-up synthesis of the potent negative allosteric glutamate N2B (GluN2B) inhibitor 1 (BMS-986169), which relies upon a stereospecific SN2 alkylation strategy and a robust process for the preparation of its phosphate prodrug 28 (BMS-986163) from parent 1 using POCl3. A deoxyfluorination reaction employing bis(2-methoxyethyl)aminosulfur trifluoride (Deoxo-Fluor) is also used to stereospecifically introduce a fluorine substituent. The optimized routes have been demonstrated to provide APIs suitable for toxicological studies in vivo.

Synthesis of fluorinated graphene oxide by using an easy one-pot deoxyfluorination reaction

The fluorination of two types of graphene oxides conducted by an easy and scalable deoxyfluorination reaction is reported. This reaction was carried out using diethylaminodifluorosulfinium tetrafluoroborate, a stable compound and an efficient reagent for replacing oxygenated functional groups of graphene oxide by fluoride. The graphene oxide produced by the Hummers’ method (GOH) showed lower reactivity than that produced by the Brodie’s method (GOB). X-ray photoelectron spectroscopy indicated that the highest fluorination degree achieved was 4.7 at.% when GOB was used, and the CF character corresponds to semi-ionic bonds. Additionally, a partial reduction of GO was concomitant with the functionalization reaction. The deoxyfluorination reaction changed the crystalline structure of GO, favoring the reconstruction of Csp2 structure of the graphene lattice and reducing the number of stacked layers. The fluorination led to the modification of the electronic band structure of this material, increasing the band gap from 2.05 eV for GOB to 3.88 eV for fluorinated GOB, while for GOH the low flurionation led to a slight increase of the band gap, from 3.48 eV to 3.57 eV.

Activation of SF6 at Platinum Complexes: Formation of SF3 Derivatives and Their Application in Deoxyfluorination Reactions

AbstractThe activation of SF6 at [Pt(PR3)2] R=Cy, iPr complexes in the presence of PR3 led selectively and in an unprecedented reaction route to the generation of the SF3 complexes trans‐[Pt(F)(SF3)(PR3)2]. These can also be synthesized from SF4 and the SF2 derivative trans‐[Pt(F)(SF2)(PCy3)2][BF4] was characterized by X‐ray crystallography. trans‐[Pt(F)(SF3)(PR3)2] complexes are useful tools for deoxyfluorination reactions and novel fluorido complexes bearing a SOF ligand are formed. Based on these studies a process for the deoxyfluorination of ketones was developed with SF6 as fluorinating agent.

Activation of SF6 at Platinum Complexes: Formation of SF3 Derivatives and Their Application in Deoxyfluorination Reactions.

The activation of SF6 at [Pt(PR3 )2 ] R=Cy, iPr complexes in the presence of PR3 led selectively and in an unprecedented reaction route to the generation of the SF3 complexes trans-[Pt(F)(SF3 )(PR3 )2 ]. These can also be synthesized from SF4 and the SF2 derivative trans-[Pt(F)(SF2 )(PCy3 )2 ][BF4 ] was characterized by X-ray crystallography. trans-[Pt(F)(SF3 )(PR3 )2 ] complexes are useful tools for deoxyfluorination reactions and novel fluorido complexes bearing a SOF ligand are formed. Based on these studies a process for the deoxyfluorination of ketones was developed with SF6 as fluorinating agent.

Deoxyfluorinations continue to evolve

Once upon a time, carrying out a deoxyfluorination reaction to replace an alcohol group with fluorine required using brutish reagents such as sulfur tetrafluoride gas or the sulfur fluoride-based l...