This chemist erroneously predicted that a certain cyclization undergoes a two-plus-two mechanism followed by a migratory insertion, which was corrected by E. J. Corey’s three-plus-two mechanism in a decade-long feud. A reaction named for this chemist expands on one developed by the Upjohn Company (10[1])and may use a commercial “AD (“A-D”) mix” containing various potassium salts and a quinine ligand. This chemist is the alphabetically latest of the developers of a copper-catalyzed (-5[1])variant of the Huisgen (“HOUSE-gun”) cycloaddition, which reacts an azide with an alkyne. This chemist names an alkene dihydroxylation (10[1])that uses osmium tetroxide, as well (10[1])as an asymmetric epoxidation. For 10 points, name this American chemist who coined the term “click chemistry” (10[2])and twice (10[1])received the Nobel Prize in Chemistry. ■END■ (0[5])