Synthesis 2006(14): 2385-2391  
DOI: 10.1055/s-2006-942386
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Optically Active 14α- and 14β-Cheilanthanic Esters

Nicon Ungur*a,b, Veaceslav KulciŢkia,b, Margherita Gavagnina, Francesco Castelluccioa, Guido Ciminoa
a Istituto di Chimica Biomolecolare, CNR, Via Campi Flegrei 34, 80078 Pozzuoli (Na), Italy
b Institutul de Chimie al Academiei de ŞtiinŢe a RM, str. Academiei 3, 2028 Chişinãu, Republic of Moldova
Fax: +373(22)739954; e-Mail: n_ungur@yahoo.co.uk;
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Publikationsverlauf

Received 8 February 2006
Publikationsdatum:
08. Mai 2006 (online)

Abstract

Isomeric cheilanthane sesterterpenoids have been obtained stereospecifically by two different synthetic pathways. Superacidic, low-temperature cyclization of C25 substrates (13E-bicyclogeranylfarnesoic acid methyl esters) led to 14α-cheilanthanes , along with other compounds, whereas the side-chain extension of a C20 precursor (ent-isocopalic alcohol) afforded 14β-cheilanthanes. The synthesized compounds could be considered as useful synthons in the preparation of bioactive natural cheilanthanes and structurally related sesterterpenoids.