New Methoxytriterpene Dione from the Cuticle of Picea jezoensis var. jezoensis

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.