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Synthesis 2010(13): 2223-2232  
DOI: 10.1055/s-0029-1218806
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Connecting C19 Norditerpenoids to C20 Diterpenes: Total Syntheses of 6-Hydroxy-5,6-dehydrosugiol, 6-Hydroxysugiol, and Taiwaniaquinone H, and Formal Synthesis of Dichroanone

Chandan Kumar Janaa, Rosario Scopellitib, Karl Gademann*a
a Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
b X-Ray Unit, EPFL SB ISIC-GE, 1015 Lausanne, Switzerland
Fax: +41(61)2671145; e-Mail: karl.gademann@unibas.ch;
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Publication History

Received 3 May 2010
Publication Date:
28 May 2010 (online)

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Abstract

Oxidation of the B-ring of abietane derivatives by Sharpless­ dihydroxylation gave the natural products 6-hydroxy-5,6-dehydrosugiol and 6-hydroxysugiol. Moreover, further oxidation gave a hydroxy dione derivative that provides a synthetic entry into the C19 taiwaniaquinoid family of natural products. This route is based on biosynthetic considerations and involves a benzilic acid rearrangement followed by decarboxylation. On the basis of this approach, a total synthesis of (-)-taiwaniaquinone H and a formal synthesis of (-)-dichroanone have been achieved.

Key words

terpenoids - biomimetic synthesis - biosynthesis - oxidations - stereoselective synthesis - total synthesis