Issue 3, 2009

Bismuth triflate-catalyzed Wagner-Meerwein rearrangement in terpenes. Application to the synthesis of the 18α-oleanane core and A-neo-18α-oleanene compounds from lupanes

Abstract

The use of bismuth(III) salts as catalysts for the Wagner-Meerwein rearrangement of lupane derivatives with expansion of ring E and formation of an additional O-containing ring is reported. This process has also been extended to other terpenes, such as the sesquiterpene (−)-caryophyllene oxide. When the reaction was performed with oleanonic acid, 28,13β-lactonization occurred, without Wagner-Meerwein rearrangement. Under more vigorous reaction conditions, dehydration of the 3β-hydroxyl group and subsequent additional Wagner-Meerwein rearrangement led to the selective synthesis of A-neo-18α-oleanene compounds, in very high yields.

Graphical abstract: Bismuth triflate-catalyzed Wagner-Meerwein rearrangement in terpenes. Application to the synthesis of the 18α-oleanane core and A-neo-18α-oleanene compounds from lupanes

Supplementary files

Article information

Article type
Paper
Submitted
20 Aug 2008
Accepted
03 Nov 2008
First published
09 Dec 2008

Org. Biomol. Chem., 2009,7, 508-517

Bismuth triflate-catalyzed Wagner-Meerwein rearrangement in terpenes. Application to the synthesis of the 18α-oleanane core and A-neo-18α-oleanene compounds from lupanes

J. A. R. Salvador, R. M. A. Pinto, R. C. Santos, C. Le Roux, A. M. Beja and J. A. Paixão, Org. Biomol. Chem., 2009, 7, 508 DOI: 10.1039/B814448F

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