β‑Fluorovinylsulfonamide as a Highly Reactivity- and Structure-Tunable Electrophile for Covalent Targeting of Proteins

Covalent targeting of proteins with small molecule probes
is a
powerful approach for analyzing and manipulating biological functions.
Recent advancements in the design of target selective covalent ligands
further expand the scope of accessible proteins in this approach.
Here we report β-fluorovinylsulfonamide (FVS) as a versatile
electrophile for the design of covalent ligands. FVS irreversibly
reacts with cysteine residues in proteins to afford stable vinyl sulfide
adducts. The reactivity of FVS is maintained with the introduction
of various substituents at the β-position, allowing for fine-tuning
of the electrophilic reactivity and flexible molecular design of FVS-based
covalent ligands. These reaction properties were leveraged in the
development of highly selective covalent ligands for RSK2 and BTK.
FVS compounds are also able to react with lysine residues in proteins
to form enamine-type reversible covalent adducts, which are susceptible
to hydrolysis under neutral aqueous conditions. This lysine reactivity
of FVS led to the discovery of FVS compound 53 as a reversible
covalent ligand for PFKL, which selectively reacts with K677 of PFKL
and allosterically upregulates PFKL activity in living cells.