Synfacts 2019; 15(08): 0841
DOI: 10.1055/s-0039-1690444
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New York

Synthesis of (–)-7-Deacetoxyalcyonin Acetate

Contributor(s):
Erick M. Carreira
,
Michael A. Imhof
MacMillan DW. C, Overman LE. * University of California, Irvine, USA
Enantioselective Total Synthesis of (–)-7-Deacetoxyalcyonin Acetate. First Synthesis of a Eunicellin Diterpene.

J. Am. Chem. Soc. 1995;
117: 10391-10392
Further Information

Publication History

Publication Date:
18 July 2019 (online)

 

Significance

The eunicellin diterpenes feature a synthetically challenging tricyclic ring system, including a hydroisobenzofuran and oxonane subunit. MacMillan and Overman reported in 1995 the first synthesis of a member of this natural product family in asymmetric fashion, confirming the relative and absolute configuration proposed by the isolation team. Highlights of this synthesis include use of a Prins–pinacol rearrangement to access the hydroisobenzofuran core as well as a photolytic deformylation of a β,γ-desaturated aldehyde.


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Comment

The synthesis commences with regio­selective opening of A, which was converted into aldehyde E in three steps. Dienyl iodide F was accessed in three steps starting with (S)-carvone. ­Fusing the two fragments set the stage for Prins–­pinacol rearrangement, affording I as a single stereoisomer. Deprotection and photolytic deformylation afforded intermediate J. The final oxonane ring was constructed using Nozaki–Hiyama–Kishi coupling, the natural product in two additional steps.


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