Fourth volume of a classic in the field of organic synthesis, describing retrosynthetic analysis and total synthesis of important molecules Classics in Total Synthesis IV is a compilation of highly important synthetic methods which lead to complex molecules with valuable properties. From the complex architectures of natural products to the streamlined synthesis of functional molecules, each chapter in Classics in Total Synthesis IV unfolds a unique story. The interplay of mechanisms, reactivity, selectivity, and stereochemical aspects is thoroughly examined, echoing the pedagogical format that has become synonymous with this series. Well-designed graphics are included throughout, and all important parts of the reaction sequences are highlighted. This volume encapsulates the culmination of new methodologies, emerging trends, and a selection of significant total syntheses undertaken from 2009 to 2022 while additionally including two earlier syntheses from 1979 and 1992 for comparison and to highlight the development of organic synthesis over the past decades. The careful balance between historical context, comments on the molecules' impact to humankind, and the design and execution aspects of each synthesis creates a narrative that is not only clear but also intellectually stimulating. Written by K. C. Nicolaou, Ruocheng Yu and Stephan Rigol, Classics in Total Synthesis IV includes 16 chapters covering: Coupling and rearrangement reactionsRecent advances in nonenzymatic enantioselective cyclizationCycloaddition and annulation reactionsC−H functionalization and transition metal-mediated C−H activationElectroorganic chemistry and visible-light photoredox catalysisHAT-initiated olefin hydrogenation, isomerization, and hydrofunctionalizationJoining its predecessors in weaving together the threads of scientific discovery, challenge, and intellectual pursuit and establishing strong connections with biology and medicine, Classics in Total Synthesis IV is an essential reference for all future and present synthetic organic chemists.