Unified Asymmetric Total Syntheses of (-)-Alotaketals A-D and (-)-Phorbaketal A

Hang Cheng; Zhihong Zhang; Hongliang Yao; Wei Zhang; Jingxun Yu; Rongbiao Tong

doi:10.1002/anie.201704628

Unified Asymmetric Total Syntheses of (-)-Alotaketals A-D and (-)-Phorbaketal A

Angew Chem Int Ed Engl. 2017 Jul 24;56(31):9096-9100. doi: 10.1002/anie.201704628. Epub 2017 Jun 26.

Authors

Hang Cheng¹, Zhihong Zhang¹, Hongliang Yao¹, Wei Zhang¹, Jingxun Yu¹, Rongbiao Tong¹

Affiliation

¹ Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, HK, China.

PMID: 28574668
DOI: 10.1002/anie.201704628

Abstract

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.

Keywords: cyclizations; epoxides; natural products; terpenoids; total synthesis.

Publication types

Research Support, Non-U.S. Gov't