This review describes ylide 1,3-dipoles in cycloaddition reactions for the synthesis (and formal synthesis) of natural products. Examples using azomethine ylides, carbonyl ylides, nitrones, nitronates, nitrile oxides and azides are provided. These lead to a diverse array of heterocyclic products. Intramolecular cycloaddition provides two new rings in one step and hence an efficient entry to complex target compounds.
Keywords: Cycloaddition, dipoles, natural products, synthesis, ylides