0000000000131548
AUTHOR
Christian Cavé
Stereocontrolled approach to quinuclidine derivatives
Abstract Asymmetric Michael-type cyclization of chiral enamino ester (S)-7 furnished the quinuclidinone derivative (3R, 4S)-5, with a high degree of stereoselectivity.
New ursolic and betulinic derivatives as potential cytotoxic agents.
Fifteen new ursolic and betulinic triterpenoids, bearing various functionalities at C-3 and C-28 were synthesized as potential cytotoxic agents. All compounds were obtained by a hemisynthetic route via ursolic and betulinic acids. Preliminary screening of these compounds on human HT 29 colon cancer cells revealed inhibitory activity for three of them. Beta-D-Glucopyranosyl-3beta-hydroxyurs-12(13)-en-28-oate 1c, 3beta-3-(3-pyridyl)-prop-2-enoyloxyurs-12(13)-en-28-oic acid 1i and the potassium salt of 3beta-cinnamoyloxylup-20(29)-en-28-oic acid 2d demonstrated cytotoxic activity in the micromolar range: 8.0, 45.0 and 8.0 microM, respectively.
A review of natural and modified betulinic, ursolic and echinocystic acid derivatives as potential antitumor and anti-HIV agents.
The aim of this review is to update current knowledge on the betulinic, ursolic and echinocystic acids and their natural and semisynthetic analogs, focussing on their cytotoxic and anti-HIV activities. Then, the last results of the authors' team on unusual semisynthetic derivatives of these triterpenoids will be presented in order to establish structure/activity relationships.
Mukaiyama-type, eight-membered ring closure: Access to a tricyclic system related to taxanes
Abstract Addition of Me2CuLi, with in situ trapping by TMSCl, to Hagemann's ester derivative 13, furnished silyl enol ether 14. Mukaiyama-type cyclization of the latter compound gave the tricyclic derivative 15, structurally related to the taxane core.