Synthetic studies toward the kempane diterpenes. Approaches to the assembly of the ring system

Citation
Gl. Bao et al., Synthetic studies toward the kempane diterpenes. Approaches to the assembly of the ring system, J CHEM S P1, (20), 2001, pp. 2657-2668
Citations number
20
Categorie Soggetti
Chemistry & Analysis","Organic Chemistry/Polymer Science
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1
ISSN journal
14727781 → ACNP
Issue
20
Year of publication
2001
Pages
2657 - 2668
Database
ISI
SICI code
1472-7781(20011021):20<2657:SSTTKD>2.0.ZU;2-K
Abstract
The ring system of the kempane diterpenes has been assembled from the Diels -Alder adduct 7 by a highly chemo- and stereoselective attack of lithium et hoxyacetylide on its apparently more encumbered carbonyl (to give 11), remo val of the silyl protecting group (12 and 13), concomitant deoxygenation an d ethoxyethyne solvolysis (18 and 19), reconjugation and epimerization (21) , and then a series of reductive and protection steps before cyclization of the final seven-membered ring (31): An alternative approach is outlined wh ich was thwarted by an unusual cyclization of a dimethyl ether moiety (48) to a tetrahydrofuran (49).