Abstract
The study of the chemical conversion of l-abietic acid (1), main component of pine rosin, into optically active natural products with biological activity has been developed at the Institute of Physical and Chemical Research by the late Dr. Akira Tahara. This group's recent works are reviewd for his memory by his staffs.
Various types of the acid rearrangements in phenacylidene derivatives of (1) were disclosed and applied to the syntheses of the A-ring substituted diterpenes and a possible intermediate to grayanotoxins. Selective functionalization at 11-, 13-and 14-positions of the aromatic C-ring were established. The 11-substitution reaction was applied to the synthesis of taxodione. Ozonolysis of the phenolic C-ring was proved to be a convenient method for the cleavage of the ring and used for the short-step synthesis of drimane-type sesquiterpenes. Modifications of the isopropyl group, including its methyl migration, made it possible to synthesize d-phyllocladene, d-kaurene, and the skeletons of pimaric acid and steroids. Finally, the synthesis of gibberellin A12 was completed by the combination of the skeletal transformation and the functionality modification of (1).
