Design of Tunable Covalent chemical functional groups via Phosphorus Fluoride Exchange (PFEx)

Covalent inhibitors achieve sustained target engagement through irreversible binding. However, excessive intrinsic electrophilicity may lead to off-target crosslinking, whereas insufficient reactivity limits effective target coverage. Consequently, the critical challenge lies not only in designing reactive covalent "warheads" but also in achieving their precise and effective modulation. Covalent drugs specifically designed to selectively target cysteine residues face limitations, as many therapeutic targets do not possess exposed cysteine residues. To broaden the scope of covalent drug discovery, there is an urgent need to develop novel electrophilic chemical scaffolds capable of targeting a diverse range of amino acid residues. P(V)-F electrophiles offer a unique structural motif wherein reactivity can be modulated through substituent effects. This study provides a comprehensive evaluation of P(V)-F electrophiles across multiple dimensions, including hydrolytic stability, biological reactivity, protein modification efficacy, and metabolic stability.