Cumulenes are organic molecules with two or more cumulative (consecutive) double bonds. Their reactions often proceed at room temperature, with or without a catalyst, and are stereospecific, giving the reaction products in high yields – features characteristic of “click reactions”. Cumulenes in Click Reactions presents a comprehensive list of cumulene systems and their reactions, with an emphasis on their “click-like” nature. The chapters are structured according to the number of carbon atoms in the system, including coverage of: introduction to the chemistry of cumulenes one-carbon cumulenes: sulfines, sulfenes, thiocarbonyl S-imides, thiocarbonyl S-sulfides, and 1-aza-2-azoniaallene salts two-carbon cumulenes: carbon oxides, carbon sulfides, carbon nitrides (isocyanates, isothiocyanates, and carbodiimides), phosphaallenes, and diarsaallenes 1,2-dicarbon cumulenes: ketenes, thioketenes, ketenimines, 1-silaallenes, 1-phosphaallenes, and other metal allenes 1,3-dicarbon cumulenes: thiocarbonyl S-ylides, 2-azaallenium salts, 1-oxa-3-azoniabutatriene salts, 1-thia-3-azoniabutatriene salts, and phosphorous ylides 1,2,3-tricarbon cumulenes: allenes, butatrienes, higher cumulenes and heterobutatrienes noncarbon cumulenes: azides, triazaallenium salts, sulfur oxides, sulfur nitrides, N-sulfinylamines, sulfurdiimides, and dithionitronium cation Cumulenes in Click Reactionsis an essential guide for researchers and advanced students in academia and research working in synthetic organic, inorganic and bioorganic chemistry.