| abstract |
Intermediate compounds for the preparation of endothelin-receptor antagonist triterpene compounds have the formulan n wherein R 2 is hydrogen or -R 3- R 4 wherein R 3 is -SO 3 -, -CH 2 COO-, -COCOO-, or -COR 5 COO- wherein R 5 is C 1 - C 6 alkylene or up to C 6 alkenylene, R 4 is hydrogen, straight or branched C 1 - C 6 alkyl and R 6 is t-butoxycarbonyl or hydrogen, or a pharmaceutically acceptable salt thereof. |