We look at the progress organic chemist Robert Woodward achieved in the 20th century in organic synthesis, that is, creating from scratch all sorts of natural products. His first success was during World War II in synthesizing quinine. Then he was able to create strychnine, cholesterol, cortisone, lysergic acid, reserpine, chlorophyll, cephalosporin, and colchicine. These syntheses took a dozen to two dozen separate chemical reactions. His pinnacle of synthesis was the 1972 co-creation of Vitamin B12. We look at one of the most important mid-20th-century theoretical results of his work: the Woodward-Hoffman rules, co-invented with Holocaust survivor Roald Hoffman. Patreon supporters can download a supplemental sheet to show some diagrams of these molecules.Support the show Support my podcast at https://www.patreon.com/thehistoryofchemistry Tell me how your life relates to chemistry! E-mail me at steve@historyofchem.com Get my book, O Mg! How Chemistry Came to Be, from World Scientific Publishing, https://www.worldscientific.com/worldscibooks/10.1142/12670#t=aboutBook