Total Synthesis of Ryanodane Diterpenoids Garajonone and 3‐epi‐Garajonone

• Published in: Angewandte Chemie International Edition Vol. 64; no. 5; pp. e202417647 - n/a
• Main Authors: Qiao, Jin‐Bao, Meng, Long, Pei, Jia‐Yi, Shao, Hui, Zhao, Yu‐Ming
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 27.01.2025; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Biosynthesis; Carbonyls; cascade reactions; Chemical reactions; Chemical synthesis; Chemistry; Chemistry, Multidisciplinary; Diterpenes; diterpenoids; Esterification; Natural products; Oxidation; Palladium; palladium-catalyzed cyclization; Physical Sciences; Science & Technology; Terpenes; total synthesis; Valence; palladium-catalyzed cyclization; cascade reactions; diterpenoids; total synthesis; ANTIFEEDANT
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202417647

Ryanodane diterpenes are structurally complex natural products that are well‐known for their high degree of oxidation and the challenges associated with synthesizing them within the terpene class. Herein, we present a two‐stage synthetic strategy that draws inspiration from the broad biosynthesis of terpenes, allowing us to achieve the first chemical synthesis of garajonone, a ryanodane diterpenoid that occurs naturally at low abundance, as well as its epimer, 3‐epi‐garajonone. The key to this success lies in the rapid construction of the carbon framework of the target molecule by employing an early‐stage palladium‐catalyzed Heck/carbonylative esterification cascade annulation, followed by successive late‐stage selective redox manipulation to establish the desired oxidation state of the molecule. This research not only showcases the synthesis of garajonone and its epimer but also provides a platform for the chemical synthesis of other members and analogs of this complex diterpenoid family. A two‐stage synthetic strategy inspired by terpene biosynthesis culminated in the first chemical synthesis of garajonone and its epimer. The rapid construction of the carbon framework using palladium‐catalyzed reactions and selective redox manipulation offers a platform for the synthesis of further members of this complex family of ryanodane diterpenoids.