Diversity Oriented Clicking: Synthesis of beta-Substituted Alkenyl Sulfonyl Fluorides as Covalent Human Neutrophil Elastase Inhibitors

Diversity Oriented Clicking (DOC) is a discovery method geared towards the rapid synthesis of functional libraries. It combines the best attributes of both classical and modern click chemistries. DOC strategies center upon the chemical diversification of core “SuFExable” hubs – exemplified by 2-Substituted-Alkynyl-1-Sulfonyl Fluorides (SASFs) – enabling the modular assembly of compounds through multiple reaction pathways. We report here a range of stereoselective Michael-type addition pathways from SASF hubs including reactions with secondary amines, carboxylates, 1H-1,2,3-triazole, and halides. These high yielding conjugate addition pathways deliver unprecedented beta-substituted alkenyl sulfonyl fluorides as single isomers with minimal purification, greatly enriching the repertoire of DOC and holding true to the fundamentals of modular click chemistry. Further, we demonstrate the biological function – another key objective of click chemistry – of this new scaffold as covalent inhibitors of human neutrophil elastase (hNE). The ease of diversification of SASFs through click pathways, enabling rapid access to biologically important molecules, further validates Diversity Oriented Clicking as an effective and robust method for lead discovery.