Determination of the absolute stereochemistry of lupane triterpenoids by fucofuranoside method and ORD spectrum

The absolute configurations of the secondary alcohols at C-3 position in betulinic acid and 3-epibetulinic acid have been unambiguously determined as S - and R -configurations, respectively, based on the fucofuranoside method. The absolute stereochemistry of 3α, 27-dihydroxylupen-20(29)-en-28-oic acid methyl ester, a potent topoisomerase II inhibitor, was determined to be 3 R , 5 R , 8 R , 9 R , 10 R , 13 R , 14 S , 17 S , 18 R , and 19 R by NMR and ORD spectroscopic studies.