Rapid and Additive-Free Synthesis of β-Sulfido Sulfonyl Fluorides through <i>N</i>-Methyl-2-pyrrolidinone (NMP)-Promoted Thia-Michael Addition

β-Sulfido sulfonyl fluorides, incorporating a clickable sulfonyl fluoride and a thioether motif, are valuable intermediates in chemical biology, materials science, and drug discovery. Herein, we developed a rapid and additive-free synthesis of these compounds via <i>N</i>-methyl-2-pyrrolidinone (NMP)-promoted thia-Michael addition of thiols to ethene sulfonyl fluoride (ESF). The reaction proceeds smoothly under neutral conditions without the need for a base or catalyst, achieving high efficiency within 20 min. This method demonstrates a broad substrate scope, tolerating thiophenols, alkylthiols, thioglycosides, and cysteine-containing peptides. The resulting β-sulfido sulfonyl fluorides enable diverse transformations, such as sulfur(VI) fluoride exchange (SuFEx) reaction and thioether oxidation, facilitating applications in drug conjugates and materials, such as additives for lithium-ion battery electrolyte components.