Discovery of Chemoselective and Biocompatible Reactions Using a High‐Throughput Immunoassay Screening

An immunoassay-based method was used to screen numerous combinations of dipoles and dipolarophiles for their ability to undergo chemoselective and biocompatible [3+2] cycloaddition reactions. The approach fulfills most of the requirements of the click concept and led to the discovery of a copper-catalyzed reaction that generates pyrazoles from sydnone and alkyne reagents.