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Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diterpenes with potential bioactivity

Paper ID Volume ID Publish Year Pages File Format Full-Text
43469 45971 2008 8 PDF Available
Title
Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diterpenes with potential bioactivity
Abstract

Kaurenic and grandiflorenic acids are naturally occurring diterpenes whose biological activity has been described. Both acids contain an exocyclic methylenic double bond that allows further functionalization on their structure. In an attempt to expand the number of derivatives of these two natural products, we have undertaken a study on the hydroformylation of the methyl esters of the two acids and the trimethylsilyl ether of kaurenol. These substrates have been hydroformylated by using unmodified Rh catalysts, as well as Rh/PPh3 and Rh/tris-(o-t-butylphenyl)phosphite catalytic systems at 100 °C and 20 bar of CO/H2 (1:1). For the three substrates, the two Rh catalysts modified with P-donor ligands, produced high conversions and chemo- and regioselectivities in the diastereoisomeric pair of linear aldehydes. In all cases, the stereoselectivity observed is strongly dependent of the system used, being the most diastereoselective the least hindered unmodified Rh/CO catalyst. A correlation between the higher diastereoselectivity and the faster β-elimination of the metal-alkyl intermediate observed in the unmodified system is discussed.

Graphical abstractKaurenic and grandiflorenic acids are naturally occurring diterpenes whose biological activity has been described. These substrates have been hydroformylated by using unmodified Rh catalysts, as well as Rh/PPh3 and Rh/tris-(o-t-butylphenyl)phosphite catalytic systems. For the three substrates, the two Rh catalysts modified with P-donor ligands, produced high conversions and chemo- and regioselectivities in the diastereoisomeric pair of linear aldehydes. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Diterpenes; Kauranes; Hydroformylation; Rhodium; Phosphite; Phosphine
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Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diterpenes with potential bioactivity
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 340, Issue 2, 1 June 2008, Pages 212–219
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us