Seven new dammarane triterpenes from the floral spikes of Betula platyphylla var. japonica.

Seven new dammarane-type triterpenoids, including two 20(S)-hydroxy-25-methoxy-dammar-23-enes (1 and 2), two 20(S),24(R)-epoxydammaranes (3 and 4), a cabralealactone (5), and two 20(S),25-epoxydammaranes (6 and 7), together with seven known triterpenes (8-14), were isolated from the floral spikes of Betula platyphylla var. japonica. The structures for all compounds were elucidated by the analyses of extensive spectroscopic data, as well as chemical examinations.