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Evolution of a Unified Strategy for Complex Sesterterpenoids: Progress toward Astellatol and the Total Synthesis of (−)‐Nitidasin
Author(s) -
Hog Daniel T.,
Huber Florian M. E.,
JiménezOsés Gonzalo,
Mayer Peter,
Houk Kendall N.,
Trauner Dirk
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201501423
Subject(s) - stereocenter , total synthesis , enantioselective synthesis , isopropyl , chemistry , substituent , stereochemistry , organic synthesis , steric effects , organic chemistry , catalysis
Abstract Astellatol and nitidasin belong to a subset of sesterterpenoids that share a sterically encumbered trans ‐hydrindane motif with an isopropyl substituent. In addition, these natural products feature intriguing polycyclic ring systems, posing significant challenges for chemical synthesis. Herein, the evolution of our stereoselective strategy for isopropyl trans ‐hydrindane sesterterpenoids is detailed. These endeavors included the synthesis of several building blocks, enabling studies toward all molecules of this terpenoid subclass, and of advanced intermediates of our initial route toward a biomimetic synthesis of astellatol. These findings provided the basis for a second‐generation and a third‐generation approach toward astellatol that eventually culminated in the enantioselective total synthesis of (−)‐nitidasin. In particular, a series of substrate‐controlled transformations to install the ten stereogenic centers of the target molecule was orchestrated and the carbocyclic backbone was forged in a convergent fashion. Furthermore, the progress toward the synthesis of astellatol is disclosed and insights into some observed yet unexpected diastereoselectivities by detailed quantum‐mechanical calculations are provided.