No abstract

SummaryDehydration of abiet-8-ene-7/i, 13P-diol (ibozol, 1) leads to abieta-7,9 (1 1)-dien-13B-01 (2) which aromatizes slowly to the known abieta-8,11,13-triene (3). Photosensitized oxygenation of the heteroannular diene 2 yields a mixture from which three compounds were identified: abiet-7-ene-9n, 11 a , 13P-trio1 (4), abieta-8,11,13-trien-7-one (5), and abieta-8,11, 13-trien-7 u-01 (6).Introduction. -There is considerable interest in the potent anti-leukemic activity and cytotoxicity of certain naturally occurring oxygenated diterpenes [ 1-31 and various synthetic approaches have been recently described [4]. In view of our interest in potential anti-tumoral agents, we report on the photosensitized oxygenation of the previously unknown heteroannular diterpene, abieta-7,9 (1 I)-dien-13 /3-01 (2), prepared from ibozol (1, abiet-8-ene-7b, 13P-diol) a diterpene isolated from the Labiatae Zboza riparia NE BROWN [5]. The photosensitized oxygenation of simpler substrates is well known [6] but few examples are documented in the diterpenoid series [7].

Durch Dehydratisierung entsteht aus dem Diol (I) ein trennbares Gemisch aus der Titelverbindung (II) und dem Trien (III).