Sulfonyl-Imidazopyridines Decouple Reactivity from Stability for Ligandability Mapping and Covalent Inhibitor Discovery
Covalent probes and therapeutics must balance electrophilicity and stability for function in biological systems, yet gains in stability can sacrifice proteome coverage and limit ligand discovery. Here, we show that single-atom N-to-C substitutions of sulfonyl purines at the nucleofuge position decouple reactivity from stability. Systematic chemical proteomic profiling identifies sulfonyl-imidazopyridines as a class of electrophiles with enhanced cellular and in vivo stability while retaining tunable reactivity toward functional tyrosine and lysine sites. These electrophiles expand access to proteomic sites not engaged by parent sulfonyl-purines or related -triazoles. Importantly, the differential binding of N7- vs N9-sulfonyl-imidazopyridine regioisomer pairs expedites the discovery of proteome-wide-selective inhibitors of metabolic targets, including lanosterol synthase (LSS), phosphoglycerate mutase 1 (PGAM1), and DCTP pyrophosphatase 1 (DCTPP1). Collectively, this work establishes a general strategy for stabilizing electrophiles and introduces a platform for global ligandability mapping guided by regioselective recognition.