# Synthesis of α -Pentafluorosulfanylated- β 2,3 -Amino Esters

Thi Mo Nguyen, Guilhem Colomer, Oscar Maugue-Sauze, Nicolas Blanchard,
Vincent Bizet, Dominique Cahard

► To cite this version:

Thi Mo Nguyen, Guilhem Colomer, Oscar Maugue-Sauze, Nicolas Blanchard, Vincent Bizet, et al. Synthesis of α -Pentafluorosulfanylated- β 2,3 -Amino Esters. ChemistryEurope, 2025, 10.1002/ceur.202500255. [https://doi.org/10.1002/ceur.20257]

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# Synthesis of α-Pentafluorosulfanylated-β²,³-Amino Esters

Thi Mo Nguyen, Guilhem Colomer, Oscar Maugue-Sauze, Nicolas Blanchard, Vincent Bizet,* and Dominique Cahard*

Incorporating the SF₅ group into organic molecules is a powerful strategy for pushing the boundaries of chemistry and driving progress in drug discovery. In this context, a synthetic route to backbone-connected pentafluorosulfanyl β-amino esters is reported, which combine the unique physicochemical properties of the SF₅ group with those of β-amino acids. The approach begins with the preparation of an unprecedented library of

(E)-α-SF₅-α₄β-unsaturated esters via aldol condensation of SF₅ aceta-tates with aldehydes. These SF₅-substituted Michael acceptors undergoes N-nucleophilic attack at the β-carbon under mild, practical conditions, affording a diverse array of α-SF₅-β²,³-amino esters. The reactions deliver excellent yields and high diastereo-selectivity, generating syn adducts with two contiguous stereo-genic centers.

## 1. Introduction

The success of peptide-based therapeutics stems from ongoing innovations in amino acid synthesis and coupling methodologies, advancements in which fluorination plays a prominent role.[¹⁻³] Incorporating fluorine atoms into peptides significantly enhances their properties, leading to improved metabolic stability, bioavailability, binding affinity, and pharmacokinetics.[⁴,⁵] In addition, specific research into peptide structure and function is facilitated by the selective placement of fluorine. Apart from the common fluoroaromatics and CF₃ moieties, the fluorine chemistry community is increasingly attracted by other highly fluorinated motifs, which can significantly modify their physical, chemical, and biological behavior, while not belonging to the PFAS category. In this context,

pentafluorosulfanyl (SF₅) compounds are at the forefront of innovation.[⁶⁻¹²] The emerging SF₅ group, with its intriguing combination of properties, appears at first sight to be able to contribute meaningfully to the bioactivity and physicochemical characteristics of peptides.[⁹,¹³,¹⁴] In 2020, Huber et al., demonstrated, through genetic encoding of p-pentafluorosulfanyl phenylalanine (SF₅Phe), the specific and strong interactions of SF₅ in proteins on account of the strongly electron-withdrawing nature, unique shape, and superhydrophobicity of the SF₅ group.[¹⁵] Moreover, the combination of high lipophilicity and stability of the pentafluorosulfanyl group improves membrane permeability and distribution capacity of SF₅Phe.[¹⁵] Despite exciting effects on peptide chemistry, the introduction of the SF₅ moiety into amino acids is still in its infancy. The pioneering synthesis of SF₅-containing aliphatic α-amino acids was achieved by Welch and coworkers in 2012, involving side-chain modification by means of SF₅Br addition to a protected allyl glycine intermediate (Figure 1).[¹⁶,¹⁷] In line with this work, in 2018 Cobb and coworkers reported the first synthesis of SF₅ aromatic amino acids using Negishi cross-coupling as a key step in C—C bond formation (Figure 1).[¹⁸] A year later, Mazuela and Johansson presented a highly enantioselective hydrogenation of furan-containing N-alkyl (aryl) imines, opening up a valuable synthetic route to chiral SF₅-substituted aromatic amino acids (Figure 1).[¹⁹] In 2021, Ung's group obtained a series of unusual amino acids containing an SF₅ moiety using common synthetic transformations: diazo coupling, reductive amination, CuAAC "click", and amide coupling reactions (Figure 1).[²⁰] Paquin and coworkers obtained one SF₅-containing aliphatic amino ester by electrochemical Kolbe hetero-coupling of acids (Figure 1).[²¹] Very recently, Guo and coworkers published two tyrosine derivatives by hydroxypentafluorosulfanylation of an acrylate or pentafluorosulfanylation of an allylic sulfone (Figure 1).[²²,²³] The first example of β-amino acids was reported by Ponomarenko and coworkers via 1,3-dipolar cycloaddition between α-SF₅-α₄β-unsaturated esters and an azomethine ylide equivalent (Figure 1).[²⁴] Tlili and coworkers described examples of four-membered ring α-SF₅-γ-amino esters as syn/anti mixtures by imino-pentafluorosulfanylation of bicyclobutane carboxylates

T. M. Nguyen, G. Colomer, O. Maugue-Sauze, D. Cahard

CNRS

UMR 6064 Institut CARMEN

Univ Rouen Normandie

INSA Rouen Normandie

ENSICAEN

Univ Caen Normandie

F-76821 Mont Saint Aignan, France

E-mail: dominique.cahard@univ-rouen.fr

G. Colomer

ENS Paris-Saclay

Université de Paris Saclay

91190 Gif-sur-Yvette, France

N. Blanchard, V. Bizet

CNRS

UMR 7042 LIMA

Université de Haute Alsace

Université de Strasbourg

68000 Mulhouse, France

E-mail: vbizet@unistra.fr

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Supporting information for this article is available on the WWW under https://doi.org/10.1002/ceur.202500255

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© 2025 The Author(s). ChemistryEurope published by Chemistry Europe and Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
<figure><img src="image_5.png" /><figcaption>**Figure 1.** Bibliographical data on SF<sub>5</sub>-containing amino acid derivatives by specific location.</figcaption></figure>

(Figure 1).<sup>[25]</sup> Currently, the state of the art in SF<sub>5</sub>-containing amino acid derivatives is largely defined by pentafluorosulfanylation on side chains or at the N- and C-termini of amino acids. To the best of our knowledge, no general protocol has yet been disclosed for synthesizing backbone-pentafluorosulfanylated α- or β-amino acids. It was against this backdrop that we set out to develop an effective

strategy toward α-SF<sub>5</sub> substituted β-amino acids (Figure 2). We hypothesized that the target products could be synthesized directly via an aza-Michael reaction of α-SF<sub>5</sub>-α,β-unsaturated esters, albeit these latter have been reported only sporadically in literature. Our initial objective was to establish an efficient access route for a wide range of α-SF<sub>5</sub> conjugated esters. In the second phase,

<figure><img src="image_6.png" /><figcaption>**Figure 2.** Our strategy for the synthesis of α-pentafluorosulfanylated-β<sup>2,3</sup>-amino acid derivatives.</figcaption></figure>
<figure><img src="image_7.png" /></figure>

we focused on developing the aza-Michael reaction to enable general access to α-SF₅-β-amino acid derivatives. A major challenge in the study was controlling the relative stereoselectivity of the two newly formed, highly functionalized, contiguous tertiary stereocenters while simultaneously preventing SF₅ elimination. Our study is particularly relevant for providing new β-amino acid derivatives in the context of α-to-β-amino acid substitutions in peptides, which often boost resistance to proteolysis.[26]

## 2. Results and Discussion

From this perspective, our study began with the preparation of α-SF₅-α,β-unsaturated esters via aldol condensation followed by crotonization. Previous reports described the selective synthesis of syn and anti aldols using titanium-, [24] boron-, [27,28] or silicon-mediated[29] aldol condensations. However, these methods are limited by narrow substrate scope and substantial side product

<figure><img src="image_8.png" /><figcaption>**Scheme 1.** Synthesis of SF₅-containing Michael acceptors 3a-n.</figcaption></figure>
<figure><img src="image_9.png" /></figure>

formation. In our case, stereocontrol at this stage was not essential, as a subsequent dehydration step was required. On the other hand, we observed that the first two steps in the synthesis of 3-SF<sub>5</sub>-pyridone reported by Carreira's group could serve as a potential pathway to the desired SF<sub>5</sub>-substituted Michael acceptors.[28] Thus, we carried out a boron-mediated aldol condensation reaction of the α-SF<sub>5</sub> acetates 1(see Supporting Information for their preparation) with various aldehydes (Scheme 1). For aromatic aldehydes, complete conversion to the corresponding aldol products was achieved after 3 h at -45 °C, yielding a mixture of two diastereoisomers with ratios ranging from 1.6:1 to 5.8:1. The aldol products then underwent dehydration through treatment with acetic anhydride (Ac<sub>2</sub>O) and 4-(dimethylamino)pyridine (DMAP) at 0 °C. After this two-step sequence, the desired Michael acceptors 3a-1 were obtained in moderate to good yields (Scheme 1). Notably, only a single stereoisomer was isolated in all cases, despite originating from a diastereomeric mixture. We assumed that products 3a-1 adopt an E configuration as indicated by the singlet observed for the vinyl proton at 7.16-7.56 ppm, whereas the corresponding proton of the Z-isomer appears as a quintet (⁴J<sub>H-F</sub>) at 7.78-7.95 ppm, as reported by Ponomarenko's group.[24] The predominant formation of the E-isomer is attributed to the steric demand of the SF<sub>5</sub> group. For alkyl aldehydes, the aldolization was also successful, reaching full conversion within 10 h and yielding a mixture of two diastereoisomers with moderate ratios ranging from 2.2:1 to 1.9:1. Unfortunately, the subsequent dehydration using Ac<sub>2</sub>O and DMAP produced a mixture of conjugated and nonconjugated products in a 1:6 ratio, respectively, due to competing elimination of the proton at either the γ- or α-position of the ester. Attempts to isomerize the nonconjugated product into the conjugated form were unsuccessful as,

counter-intuitively, the nonconjugated product was recovered (see Supporting Information for attempts of isomerization). Finally, using a weaker base, such as pyridine, in the presence of trifluoroacetic anhydride (TFAA) favored the formation of the conjugated product as the major component 3m/3m' 98:2 and 3n/3n' 90:10 (Scheme 1) (see Supporting Information for optimization of the reaction).

With a library of α-SF<sub>5</sub> conjugated esters in hand, we next turned our attention to the feasibility of aza-Michael additions toward α-SF<sub>5</sub>-β-amino acids. Our literature survey revealed that although the functionalization of α-SF<sub>5</sub>-α,β-unsaturated carbonyl derivatives via Michael reactions has been explored, successful examples have not yet been reported.[24,30] This challenge arises from the fact that under basic or nucleophilic conditions, the desired products undergo either elimination of the SF<sub>5</sub> group or C-C bond cleavage, leading to the formation of non-SF<sub>5</sub>-substituted compounds or recovery of the SF<sub>5</sub>-acetate, respectively. Very recently, Bizet and coworkers reported the addition of N- and S- nucleophiles to the electron-deficient β-carbon atom of 2-SF<sub>5</sub>-indenones, affording anti products in excellent yields with high diastereoselectivity.[31] Building on these observations, we aimed to address this critical issue by developing a practical aza-Michael addition using the obtained SF<sub>5</sub>-containing Michael acceptors.

Inspired by Zanda's work on CF<sub>3</sub>-containing analogs, we investigated the N-nucleophilic attack at the β-carbon of α-SF<sub>5</sub>-α,β-unsaturated esters in the presence of amine bases such as DABCO, DMAP, Et<sub>3</sub>N, and DBU.[32] Michael acceptor 3b was used as a model substrate to facilitate reaction monitoring via ¹⁹F NMR. Since the integral CF<sub>3</sub>/SF<sub>5</sub> ratio remained constant, we concluded that no SF<sub>5</sub> elimination occurred. Gratifyingly, using glycine

<table><caption>**Table 1.** Selected optimization data of the aza-Michael addition of α-SF<sub>5</sub>-α,β-unsaturated ester 3b.</caption><thead><tr><th>Entry</th><th>Deviations from above</th><th>Yield of 5a<sup>a)</sup></th><th>syn/anti</th></tr></thead><tbody><tr><td>1</td><td>None</td><td>&gt;98 (72)<sup>b)</sup></td><td>96:4</td></tr><tr><td>2</td><td>2 equiv. of 4a</td><td>100</td><td>84:16</td></tr><tr><td>3</td><td>DABCO instead of Et<sub>3</sub>N</td><td>83</td><td>86:14</td></tr><tr><td>4</td><td>DBU instead of Et<sub>3</sub>N</td><td>dec.</td><td>n.d.</td></tr><tr><td>5</td><td>DMAP instead of Et<sub>3</sub>N</td><td>83</td><td>27:73</td></tr><tr><td>6</td><td>Cs<sub>2</sub>CO<sub>3</sub> instead of Et<sub>3</sub>N</td><td>NR</td><td>n.d.</td></tr><tr><td>7</td><td>DCM instead of CCl<sub>4</sub></td><td>96</td><td>42:58</td></tr><tr><td>8</td><td>DMF instead of CCl<sub>4</sub></td><td>dec.</td><td>n.d.</td></tr><tr><td>9</td><td>THF instead of CCl<sub>4</sub></td><td>93</td><td>40:60</td></tr><tr><td>10</td><td>DMAP/THF instead of Et<sub>3</sub>N/CCl<sub>4</sub></td><td>&gt;98</td><td>20:80</td></tr></tbody><tfoot><tr><td colspan="4"><sup>a)</sup>Yield determined by ¹⁹F NMR of the crude mixture with PhSCF<sub>3</sub> as internal standard; <sup>b)</sup>Isolated yield.</td></tr></tfoot></table>
<figure><img src="image_10.png" /></figure>

methyl ester hydrochloride **4a** as the donor in the presence of Et<sub>3</sub>N as the base and CCl<sub>4</sub> as the solvent at 0 °C for 24 h (entry 1, **Table 1**) gave the best result, affording a high yield (>98%, calculated by <sup>19</sup>F NMR) and excellent diastereoselectivity (dr 96:4 in favor of the syn isomer, see later in the text for assignment details). Deviation from these conditions resulted in lower *dr* values but enabled separation of the two diastereomers by column chromatography. The syn isomer was fully characterized and found to be stable, whereas the anti isomer proved unstable during handling and purification, preventing complete structural assignment. We have a range of consistent evidence supporting the assignment of the anti isomer (¹H, <sup>19</sup>F NMR, HRMS, see Supporting Information), but in the absence of <sup>13</sup>C NMR and X-ray data, complete certainty cannot be claimed. Therefore, the second product can only be presumed to be the anti isomer. The retro-aza-Michael reaction and C—C bond cleavage may occur under our reaction conditions or as a degradation pathway of the anti isomer, regenerating the starting material **3b** and the α-SF<sub>5</sub> acetate **1b**. In addition, formation of the corresponding aziridine through displacement of the SF<sub>5</sub> group by attack of the

amine has occasionally been observed (see Supporting Information for characterization of the aziridine). To address stability issues, amine **5a** was quantitatively converted to its corresponding ammonium salt by treatment with 2 N HCl in Et<sub>2</sub>O, enabling long-term storage at least for the syn isomer. Increasing the amount of glycine methyl ester hydrochloride **4a** led to reduced diastereoselectivity (dr 84:16; entry 2, Table 1). Notably, the reduced diastereoselectivity observed with the less basic DABCO compared to Et<sub>3</sub>N highlights the critical influence of the nature and pKa of the base in this reaction (entry 3, Table 1). In the presence of the stronger base DBU, substrate **3b** underwent decomposition (entry 4, Table 1). Interestingly, using DMAP resulted in the same yield as DABCO but reversed the major diastereomer (entry 5, Table 1). The inorganic base Cs<sub>2</sub>CO<sub>3</sub> is incompatible with this transformation, as the Michael acceptor **3b** remained unreacted and was quantitatively recovered (entry 6, Table 1). To evaluate alternative solvents to CCl<sub>4</sub>, the optimized reaction conditions were tested using DCM, DMF, and THF (entries 7–9, Table 1); however, none yielded better results. In polar DMF, **3b** underwent decomposition. During reaction

<figure><img src="image_11.png" /><figcaption>**Scheme 2.** Scope of the aza-Michael addition reaction of α-SF<sub>5</sub>-α,β-unsaturated esters.</figcaption></figure>
<figure><img src="image_12.png" /></figure>

optimization, a reversal of diastereoselectivity was observed, although the diastereomeric ratio remained modest (entries 5, 7, and 9, Table 1). The most effective conditions for obtaining the *anti* diastereoisomer are shown in entry 10, Table 1 where the use of DMAP as the base and THF as the solvent resulted in complete conversion and a diastereoisomeric ratio of 20:80. Solvent effects alone are sufficient to invert the diastereomeric outcome of the reaction, whereas the presence of DMAP selectively affords the *anti* adduct irrespective of solvent polarity.

With the optimized conditions in hand for the synthesis of stable syn isomer 5a (Table 1, entry 1), we next investigated the scope and limitations of this unprecedented aza-Michael

addition (Scheme 2). Using glycine methyl ester 4a as the Michael donor, various α-SF₅-α,β-unsaturated esters bearing diverse functionalities exhibited excellent reactivity. The reaction tolerated both benzyl and methyl esters, delivering the corresponding products 5a and 5b in high yields with excellent diastereocontrol. A variety of Michael acceptors with electron-donating or electron-withdrawing substituents on the arene moiety also provided the desired products in high yields and with excellent diastereoselectivity 5c-k. In contrast, the sterically hindered Michael acceptor 3l, bearing o,o'-substituents, resulted in a reduced diastereomeric ratio, despite the use of propylamine, a less hindered and highly nucleophilic amine. To further

(a) **Reaction outcome in CCl₄ and SC-XRD of syn-5r.HBF₄**

<figure><img src="image_13.png" /></figure>

(b) **Stereodivergent pathways to syn-5a or anti-5a**

* syn-5a via contact zwitterion and amine-assisted protonation (same as above)

<figure><img src="image_14.png" /></figure>

* anti-5a in the presence of DMAP

<figure><img src="image_15.png" /><figcaption>**Scheme 3.** a) Rationale for the formation of the syn isomer in CCl₄/NEt₃; b) Stereodivergence in CCl₄/DMAP.</figcaption></figure>
<figure><img src="image_16.png" /></figure>

demonstrate the generality of this reaction, we assessed the reac-
tivity of Michael acceptor **3b** with a range of *N*-nucleophiles. Both
the nucleophilicity and steric profile of the amine influence the
rate of addition. Other amino esters underwent full conversion to
the corresponding products **5m-o** displaying high diastereoselec-
tivity (up to 95:5 *dr*). For highly nucleophilic amines such as ben-
zylamine and allylamine, the reactions proceeded smoothly
without the need for added Et₃N, whereas the reaction with
the less nucleophilic propargylamine remained incomplete, even
after an extended reaction time. The applicability of our method
was further demonstrated through a gram-scale experiment,
which afforded product **5q.HCl** in quantitative yield. Aniline could
also serve as a Michael donor, although the conversion was low
(46%, adducts not isolated). However, when switching from *β*-aryl
(**3a-I**) to *β*-alkyl (**3m-n**) unsaturated esters, significantly higher
conversions were observed with aniline (>95%), likely due to
increased electrophilicity at the *β*-carbon caused by the electron-
donating effect of the aliphatic chain. Unfortunately, the resulting
aza-Michael products were not stable enough to be isolated in
pure form after purification, the products reverted to the reac-
tants under dilution conditions. As a result, we were unable to
obtain aza-Michael adducts featuring either an aniline moiety
or an alkyl chain at the *β*-position. In some cases, the low solu-
bility of chloride salts in deuterated chloroform was observed,
which hampered the NMR characterization of the resulting prod-
ucts. To address this, the HCl solution in Et₂O was replaced with
solutions of HBF₄ or TfOH in Et₂O during the precipitation step.
Notably, this counterion exchange improved not only the solubil-
ity but also the stability of the *α*-SF₅-*β*-amino esters. Alternatively,
anion metathesis on **5n.HCl** was performed with AgBF₄ in CH₂Cl₂
to produce **5n.HBF₄**. The syn configuration of the major isomer of
**5r.HBF₄** was confirmed by single-crystal X-ray diffraction (SC-XRD)
(Scheme 3). Similarly, all aza-Michael adducts **5a-u** displayed
consistent NMR spectral features, specifically a large coupling
constant (³J<sub>H-H</sub> = 9.4–10.9 Hz) between the *α*- and *β*-hydrogens
adjacent to the carbonyl group. Based on this, we inferred that
all products possess the same syn configuration. This relative con-
figuration can be explained by a diastereoselective protonation
step as the key stereo-defining event. Following nucleophilic
addition of the amine to the Michael acceptor, a zwitterionic eno-
late intermediate forms and undergoes protonation. In apolar
CCl₄, a contact zwitterion forms, and *Si*-face protonation of this
intermediate leads to the observed syn-configured Michael
product **syn-5r** (*dr* 95:5) (Scheme 3a). The C-protonation of the
contact zwitterionic enolate could proceed via an intramolecular
pathway with assistance of the triethylamine[³³,³⁴] to yield **syn-5r**
(Scheme 3a). In the Newman projection, conformation *A* is highly
sterically hindered, allowing free rotation to produce a less hin-
dered conformation *B*, which was captured by the X-ray structure
(Scheme 3a).[³⁵,³⁶] The relative configuration determined in the
solid-state by SC-XRD, along with the solution-phase conforma-
tion confirmed by the measured ⁴J<sub>H-F</sub> coupling constant in the
NMR spectrum, supports the assignment of conformation *B* to
**5r.HBF₄** (Scheme 3a). The stability of this conformation *B* is pri-
marily driven by relief of steric congestion.

Stereodivergence was demonstrated by the selective formation of either **syn-5a** or **anti-5a** (Scheme 3b). The combination of Et₃N and CCl₄ produced **syn-5a** (*dr* 96:4), following the same pathway proposed for the analogous **syn-5r**. In contrast, in the presence of DMAP, regardless of whether CCl₄ or THF is used, the reaction is proposed to proceed via intermediate **A** (Scheme 3b). The primary addition product, i.e., the *β*-NH₂⁺ ester enolate, was deprotected by DMAP leading to intermediate **A**, which adopts a conformation that minimizes allylic 1,3-strain.[³⁷] The protonated DMAP (DMAPH⁺), through its iminium resonance form, engages in charge association with the enolate oxygen and forms a hydrogen bond between its NH group and the nucleophilic nitrogen of the glycine moiety. In intermediate **A**, subsequent *Re*-face protonation is favored yielding the major Michael product **anti-5a** (*dr* 80:20) (Scheme 3b). When pyridine was used as the base, the reaction showed lower diastereoselectivity (*dr* 58:42), which supports the involvement of intermediate **A**. Finally, treatment of **syn-5a** (*dr* 96:4) with DMAP in THF at room temperature rapidly equilibrated the mixture to give **anti-5a** (*dr* 80:20) within minutes; however, treatment of **anti-5a** (*dr* 80:20) with triethylamine in CCl₄ did not affect the diastereomeric equilibrium (Scheme 3b).

**3. Conclusion**

In summary, we developed a practical method to synthesize a
series of (E)-*α*-SF₅-*α*,*β*-unsaturated esters via aldol condensation
of SF₅ acetates with aldehydes. These Michael acceptors enabled
aza-Michael addition with various amines and amino acid deriva-
tives, yielding a new library of linear *α*-pentafluorosulfanylated-*β*²,³-
amino esters. The reactions exhibited high diastereoselectivity, and
the aza-Michael addition was rendered stereodivergent by adjust-
ing solvent polarity or the nature of the base. However, only the
syn isomers remained stable for subsequent uses, while the *anti*
isomers were prone to decomposition. With the growing use of
the SF₅ moiety in drug design, the peptide-like scaffolds presented
here may offer new opportunities to explore peptide structure and
function, as well as to fine-tune biological properties.

**Supporting Information**

The data that support the findings of this study are available in
the Supporting Information of this article. The authors have cited
additional references within the Supporting Information.

**Acknowledgements**

This work was supported by the French National Research Agency—
ANR Sulfive project (grant no. ANR-21-CE07-0042), University of
Rouen Normandy, the Centre National de la Recherche Scientifique
(CNRS), INSA Rouen Normandy, European Regional Development
Fund (ERDF), Labex SynOrg (ANR-11-LABX-0029), Carnot
Institute I2C, the graduate school for research XL-Chem (ANR-
18-EURE-0020XL CHEM), Université de Haute-Alsace, Université
de Strasbourg, and Université de Rouen.
<figure><img src="image_17.png" /></figure>

**Conflict of Interest**

The authors declare no conflict of interest.

**Data Availability Statement**

The data that support the findings of this study are available from the corresponding author upon reasonable request.

**Keywords:** β-amino acids · aza-Michael addition · diastereodivergence · pentafluorosulfanylated amino acids · SF₅ chemistry

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Manuscript received: July 3, 2025

Revised manuscript received: October 14, 2025

Version of record online: