Recent Advances in the Catalytic Transformations to Access Alkylsulfonyl Fluorides as SuFEx Click Hubs

Abstract

The search for new and efficient methods to access sulfonyl fluorides is of considerable research interest owing to the widespread application of these molecules in different fields. In this context, sulfur(VI) fluoride exchange (SuFEx) click chemistry is emerging as one of the most prominent such methods. The development of competent new catalytic methodologies for preparing alkylsulfonyl fluorides has become an area of special interest in organic synthesis. Compared with the substantial progress already made in the synthesis of arylsulfonyl fluorides, approaches for preparing aliphatic sulfonyl fluorides remain less explored. In this review, we summarize recent advances in four different strategies for synthesizing alkylsulfonyl fluorides: (i) photoredox catalysis, (ii) electrocatalysis, (iii) transition-metal catalysis, and (iv) organocatalysis. These reactions result in different sulfonyl fluorides that can act as bioactive molecules and building blocks suitable for further SuFEx transformation.

Introduction

Sulfonyl fluorides are important building blocks in chemical synthesis and have a diverse range of applications in materials science, chemical biology, and drug discovery.^1–3 Beginning in 2014, Sharpless and co-workers demonstrated that the sulfur(VI) fluoride exchange (SuFEx) reaction is an emerging new click reaction possessing the inimitable reactivity and stability of organosulfur fluorides.^4–6 The first-generation click reaction, the Huisgen azide–alkyne cycloaddition, has become a useful tool owing to the ligation ability of the azide and alkyne and to the utilization of mild copper catalysis.^7–10 Click reactions can work under aqueous and oxygen-tolerant conditions, resulting in excellent yields of products. Sulfonyl fluoride is more robust under acidic and basic conditions than the well-known sulfonyl chloride.¹¹

Sulfur(VI)-containing compounds have been widely used in pharmaceuticals,^12–15 materials science,¹⁶ and polymer science.¹⁷ Interesting applications of sulfonyl fluorides in biochemistry have included the inhibition of proteases and as biological probes (Figure 1, Part (a)).^18–20 The SuFEx reaction between di(arylsulfonyl fluorides) and di(aryl silyl ethers) that affords polysulfonate–SuFEx polymers has unique applications in polymer science^21–24 because of its efficiency. To synthesize the functional molecules of interest, multistep processes are required in conventional approaches (Figure 1, Part (b)). Moreover, well-designed and readily available precursors are needed to apply the catalytic processes. For example, ethenesulfonyl fluoride (ESF, H₂C=CHSO₂F) has been introduced as a good Michael acceptor for the preparation of various nitrogen-, oxygen-, and carbon-based nucleophiles that can be utilized in the synthesis of functionalized alkylsulfonyl fluorides (Figure 1, Part (c)).^25–27

In this review, we highlight new methodologies; including photoredox catalysis, electrocatalysis, transition-metal catalysis, and organocatalysis; that have been developed for the synthesis of alkylsulfonyl fluorides (Figure 1, Part (d)).

Conclusions and Outlook

We have surveyed the synthesis of alkylsulfonyl fluorides via carbon–carbon or carbon–heteroatom bond formation and their fluoride exchange (SuFEx) reaction with suitable coupling partners. Reactions of the SO₂F functional group provide access to a wide variety of carbo- and heterocycles upon activation through photoredox catalysis, electrocatalysis, transition-metal catalysis, and organocatalysis. We believe that these methods will contribute to the expansion of sulfonyl fluoride containing compound libraries for pharmaceutical and agrochemical research.

Acknowledgment

The generous support of the Ministry of Science, ICT, and Future Planning of Korea (RS-2023-00259659, RS-2023-00219859, 2020R1C1C1006440, and 2019R1A6A1A10073079) is gratefully acknowledged.

Trademarks. DABCO^® (Evonik Operations GmbH); Selectfluor^® (Merck KGaA, Darmstadt, Germany).