Total Syntheses of Rhodomolleins XX and XXII: A Reductive Epoxide‐Opening/Beckwith–Dowd Approach. Issue 25 (9th May 2019)

• Record Type: Journal Article
• Authors: Yu, Kuan; Yang, Zhen‐Ning; Liu, Chun‐Hui; Wu, Shao‐Qi; Hong, Xin; Zhao, Xiao‐Li; Ding, Hanfeng
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 25(2019)
• Page Start: 8556
• Page End: 8560
• Publication Date: 2019-05-09
• Subjects: cyclopropanation -- Diels–Alder -- radical reactions -- terpenoids -- total synthesis; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201903349
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A new Ti III ‐mediated reductive epoxide‐opening/ Beckwith–Dowd rearrangement process efficiently assembles the bicyclo[3.2.1]octane framework of highly oxidized grayanane diterpenoids. By incorporation of a Cu(tbs)2 ‐catalyzed (tbs= N ‐ tert ‐butylsalicylaldiminato) intramolecular cyclopropanation, a diastereoselective oxidative dearomatization‐induced Diels–Alder cycloaddition and a MeReO3 ‐catalyzed Rubottom oxidation, this approach has enabled the first total syntheses of rhodomolleins XX and XXII in 23 and 22 steps, respectively. Abstract : Fusing cycles : A new Ti III ‐mediated reductive epoxide‐opening/Beckwith–Dowd rearrangement efficiently assembles the bicyclo[3.2.1]octane framework of highly oxidized grayanane diterpenoids. This reaction, along with a Cu II ‐catalyzed intramolecular cyclopropanation, a diastereoselective oxidative dearomatization‐induced (ODI) Diels–Alder cycloaddition, and a MeReO3 ‐catalyzed Rubottom oxidation, were key steps in the first total syntheses of rhodomolleins XX and XXII.