Benzochromanone and Benzochromene Natural Products: Synthetic Strategies and Total Syntheses

This account overviews our synthetic strategies for natural products featuring benzochromanone and benzochromene frameworks. The total synthesis of monomeric benzochromanones, particularly xanthones and benzochromanones is achieved. Key accomplishments include the development of a versatile synthetic approach for constructing xanthone frameworks via spirochromanone intermediates and the successful total syntheses of (±)-4-deoxyblennolide C, (+)-blennolide C, and chromanone lactone gonytolide C. The asymmetric total synthesis of benzochromene (R)-(+)-teretifolione B and the first asymmetric synthesis of (R)-(+)-methylteretifolione B are also achieved. The Diels-Alder reaction between benzyne derived from chromene precursors and oxygenated furans enabled efficient access to benzochromene derivatives. The enantioselective synthesis of teretifolione B and related compound was accomplished through the enzymatic resolution of racemic chromenes, and the reaction conditions were investigated to improve regioselectivity in key steps. These synthetic routes provide access to a diverse array of benzochromanone and benzochromene derivatives with potential biological activity.