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 the synthesis 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 have 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.