Bitter Principles isolated from Simaroubaceous plants have been extensively investigated. We recently examined constituents of the root and stem bark of Ailanthus altissima SWINGLE (Japanese name: Shinju or Niwaurushi) and isolated five new quassinoids. Shinjulactones A (5) and D (6) were shown to be quassinoids with normal picrasane skeleton (1), while shinjulactones B (7), C (8), and shinjudilactone (9) were those with new migrated picrasane skeletons. On heating with sodium hydrogencarbonate in aqueous methanol ailanthone (4) afforded shinjudilactone (9) and its 13-epimer (11) in a ratio of 1:1 in good yields by benzilic acid rearrangement.
