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A novel pentacyclic triterpene dione was isolated from the cuticle of Picea jezoensis var. jezoensis together with the known serrat-14-ene-3,21-dione (1), and the structure of this compound was determined as 21α-methoxyserrat-13-ene-3,15-dione (2). Detailed NOESY experiments revealed that 2 has a chair form of ring A and a chairlike conformation of ring C, respectively, in CDCl3 solution. Interestingly, single-crystal X-ray analysis indicates that in the solid state 2 has a deformed boat form of ring A, in which the 3-oxo and the 25-methyl groups are arranged in flag-pole positions, and a chairlike form of ring C.

Three new epoxytriterpenes, 14 beta,15 beta-epoxy-21 beta-hydroxyserratan-3-one (1), 13 alpha,14 alpha-epoxy-21 alpha-methoxyserratan-3-one (2), and 13 alpha,14 alpha-epoxy-3 beta-methoxyserratan-21 beta-ol (3), were isolated together with two known triterpenoids, 21 alpha-methoxyserrat-13-en-3-one (4) and 21 beta-hydroxyserrat-14-en-3-one (5), from the cuticle of Picea jezoensis var. jezoensis. The structures of these new compounds were established on the basis of spectral data (NMR, MS) and single-crystal X-ray analyses (1 and 2) and partial synthesis (2 and 3).