The chemistry and scope of application of a series of reagents and reactions used for the formation of peptide bonds are discussed. They include: unsaturated ethers, dicyclohexylcarbodiimide, cyanamide, ketenimines, ketenes, ynamines, 1,2-oxazolium salts, EEDQ, acyloxyphosphonium salts, triphenylphosphite and imidazole, oxidation-reduction condensation, copper complexes, and silicon tetrachloride. 1. Unsaturated Ethers 1.1. α-Chlorovinyl Ethyl Ether, α,α-Dichlorodiethyl Ether, and Dichloromethyl Methyl Ether 1.2. Ethoxyacetylene 2. Dicyclohexylcarbodiimide 2.1. Dicyclohexylcarbodiimide and Additives 2.2. Complexes of DCC-Pentachlorophenol and DCC-Pentafluorophenol 3. Cyanamide 4. Ketenimines and Ketenes 5. Ynamines 6. 1,2-Oxazolium Salts 7. EEDQ 8. Acyloxyphosphonium Ions 9. Triphenylphosphite and Imidazole 10. Oxidation-Reduction Condensation 11. Copper(II) Complexes 12. Silicon Tetrachloride