This course provides an introduction to the broad field of heterocyclic organic chemistry by reviewing the major classes of heterocyclic compounds in terms of nomenclature, structure, and properties. Classical and modern heterocyclic ring synthesis and functionalization methodologies will be covered, and an array of organometallic-promoted methods will be presented. The use of heterocycles in the design and synthesis of bioactive compounds in medicinal chemistry, and as intermediates in the synthesis of natural products will be discussed.