reactions has dramatically improved the efficiency of organic synthesis. N-Heterocyclic carbene based catalysts are now widely applied in the area of synthesis of both natural products and therapeutic agents. “Science of Synthesis: N-Heterocyclic Carbenes in Catalytic Organic Synthesis” presents the most commonly used and significant metal- or non-metal-catalyzed reactions for modern organic synthesis. The basic principles and current state-of-the-art of the methods are covered. Scope, limitations, and mechanism of these reactions are discussed and key experimental procedures are included. Typical examples of target synthesis are often provided to show the utility and inspire further applications. Volume 1 provides a detailed introduction to NHCs, with discussion of their architectures and steric and electronic properties.