1.
Org Lett
; 3(5): 647-50, 2001 Mar 08.
Article
in English
| MEDLINE
| ID: mdl-11259027
ABSTRACT
[structure: see text]. The tetracyclic ketal 24, a suitable intermediate for the synthesis of antitumor pentacyclic quassinoids, has been efficiently prepared from communic acids (5a-c), via methyl ketone 9. The synthetic sequence from 9 to 24 consists of 15 steps in 12% overall yield.