Unified Asymmetric Total Syntheses of (−)‐Alotaketals A–D and (−)‐Phorbaketal A

The novel tricyclic spiroketal alotane‐type sesterterpenoids showed strikingly different biological activities and potency with subtle structural alterations. Asymmetric total syntheses of the tricyclic sesterterpenoids (−)‐alotaketals A–D and (−)‐phorbaketal A were accomplished [29–31 steps from (−...

Full description

Saved in:
Bibliographic Details
Published inAngewandte Chemie Vol. 129; no. 31; pp. 9224 - 9228
Main Authors Cheng, Hang, Zhang, Zhihong, Yao, Hongliang, Zhang, Wei, Yu, Jingxun, Tong, Rongbiao
Format Journal Article
LanguageEnglish
Published 24.07.2017
Subjects
Cyclisierungen
Epoxide
Naturstoffe
Terpenoide
Totalsynthesen
Online AccessGet full text

Cover

More Information
Summary:The novel tricyclic spiroketal alotane‐type sesterterpenoids showed strikingly different biological activities and potency with subtle structural alterations. Asymmetric total syntheses of the tricyclic sesterterpenoids (−)‐alotaketals A–D and (−)‐phorbaketal A were accomplished [29–31 steps from (−)‐malic acid] in a collective way for the first time. The key features of the strategy included 1) a new cascade cyclization of vinyl epoxy δ‐keto‐alcohols to forge the common tricyclic spiroketal intermediate, 2) a late‐stage allylic C−H oxidation, and 3) olefin cross‐metathesis to install the different side chains. Alleskönner: Ein gemeinsamer Ansatz für die Totalsynthesen der tricyclischen Sesterterpenoide (−)‐Alotaketal A–D und (−)‐Phorbaketal A liefert die Produkte in 29–31 Stufen ausgehend von (−)‐Äpfelsäure. Dabei stehen eine neue Cyclisierungskaskade von Vinylepoxy‐δ‐ketoalkoholen, eine späte C‐H‐Oxidation und eine Olefin‐Kreuzmetathese im Vordergrund.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201704628