Ursolic acid-based 24-nor- and A- seco -24-oxy-triterpenoids.

Using methyl 2-cyano-3,4- seco -12(13),4(23)-diene-ursolate as a starting scaffold a series of 3-oxo-24-nor-ursolate and A- seco -ursanes holding hydroxy-, furoyloxy-, p -tosyloxy- as well as aldehyde fragments at C24 that possess cytotoxic activity has been synthesised. The structures of the new ursanes were confirmed by detailed spectral data analysis. The chemoselectivity of methyl 2-cyano-3,4- seco -12(13),4(23)-diene-ursolate oxidation involving the double bond in the A cycle was observed.