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Polyunsaturated C‐Glycosidic 4‐Hydroxy‐2‐pyrone Derivatives: Total Synthesis Shows that Putative Orevactaene Is Likely Identical with Epipyrone A
Author(s) -
Preindl Johannes,
Schulthoff Saskia,
Wirtz Conny,
Lingnau Julia,
Fürstner Alois
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201702189
Subject(s) - cycloisomerization , chemistry , pyrone , stereochemistry , bicyclic molecule , glycosidic bond , alkyne , total synthesis , catalysis , organic chemistry , enzyme
Orevactaene and epipyrone A were previously thought to comprise the same polyunsaturated tail but notably different C‐glycosylated 4‐hydroxy‐2‐pyrone head groups. Total synthesis now shows that the signature bicyclic framework assigned to orevactaene is a chimera; the compound is almost certainly identical with epipyrone A, whose previously unknown stereochemistry has also been established during this study. Key to success was the ready formation of the bicyclic core of putative orevactaene by a sequence of two alkyne cycloisomerization reactions using tungsten and gold catalysis. Equally important was the flexibility in the assembly process gained by the use of heterobimetallic polyunsaturated modules whose termini could be selectively and consecutively addressed in a practical one‐pot cross‐coupling sequence.