NEW DITERPENES FROM SALVIA-MUNZII - CHEMICAL AND BIOGENETIC ASPECTS

Three new natural diterpenes: 5,6-didehydro-7-hydroxy-taxodone (1), 17-hydroxycryptotanshinone (2) and salvicanaraldehyde (4) plus the known compounds: taxodione, taxodone, cryptotanshinone (3), 7alpha-hydroxyroyleanone, ferruginol, 6,7-didehydroferruginol (6), 6,7-didehydrosempervirol (7), demethylsalvicanol, salvicanaric acid (5) and the 11,12-dihydroxy-6,7-secoabieta-8,11,13-trien-6,7-dial-11,6-hemiacetals 9 and 10 were isolated from the roots of Salvia munzii. The structures of the new compounds were established from their spectroscopic data and by chemical correlations. The co-occurence of some of these compounds in the one species together with the results obtained of photochemical oxidation of 5,6-didehydro-7-hydroxytaxodone supports our earlier hypothesis of a biogenetic pathway to highly oxidized abietatriene diterpenes in which enzymatic dehydrogenation and singlet-state oxygen appear to play important roles.