2.1 Introduction to CuAAC

Abstract The basic principles of the copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC), widely considered to be the first click reaction, are described. This involves amongst others the concept of click reactions, the mechanism of CuAAC, the synthesis and reactivity of organic azides and acetylenes, an overview of most commonly used copper(I) catalysts and ligands, the properties of 1,2,3-triazoles and their resemblance to amides, and a general overview of the scope and limitations of this reaction.