Kobayashi’sAryne Precursor for the One-StepSynthesis of Anthraquinones and Its Application to the Total Synthesisof Chrysophanol, Danthron, and Physcion

A one-step synthetic method to access medicinally essential anthraquinones has been developed by reacting Kobayashi’s aryne precursors with 3-sulfonylphthalides following [4 + 2] Hauser–Kraus annulation reaction. The developed method has been implemented for the total synthesis of bioactive natural products, chrysophanol, danthron, and physcion in 30, 20, and 36% overall yields, respectively, from known compounds.