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

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Peixoto, AF (Author) FCUP; de Melo, DS (Author) Other; Fernandes, TF (Author) Other; Fonseca, Y (Author) Other; Gusevskaya, EV (Author) Other; Silva, AMS (Author) Other; Contreras, RR (Author) Other; Reyes, M (Author) Other; Usubillaga, A (Author) Other; dos Santos, EN (Author) Other; Pereira, MM (Author) Other; Bayon, JC (Author) Other

Journal

Title: Applied Catalysis A: General

Vol. 340

Pages: 212-219

ISSN: 0926-860X

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 18 Citations

Scopus - 17 Citations

Other information

Authenticus ID: P-003-YMX

DOI: 10.1016/j.apcata.2008.02.015

Abstract (EN): 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/PPh(3) and Rh/tris-(o-t-butylphenyl)phosphite catalytic systems at 100 degrees C and 20 bar of CO/H(2) (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 beta-elimination of the metal-alkyl intermediate observed in the unmodified system is discussed.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8