
TY  - JOUR
A1  - Cambie, RC 
A1  - Hayward, RC 
T1  - Chemistry of the Podocarpaceae. XLVIII. Photo-sensitized oxidations of unsaturated ring-c aromatic diterpenoids
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1974
VL  - 27
IS  - 9
SP  - 2001
EP  - 2016
KW  - 
UR  - https://doi.org/10.1071/CH9742001 
N2  - Photo-sensitized oxidation of the 6,7-dehydro ring-c aromatic diterpenoids (5), (8) and (38) affords high yields of the corresponding 5-ene-7-ones (62), (63) and (69). Similar oxygenation of 13-methoxy- totara-6,8,11,13-triene (21) gives a hydroperoxide (74) which undergoes a facile rearrangement to a naphthyl derivative (80) in the presence of acid. Photo-sensitized oxidation of the enol acetates derived from the 7-oxo diterpenoids, however, provides a general method for preparation of the corresponding 5-ene-7-one. Reduction of the enone (62) with lithium aluminium hydridealuminium chloride gives a mixture of the 5,8,11,13-tetraene (66) and the 6,8,11,13-tetraene (9) while reduction with sodium borohydride and treatment of the resulting alcohols (61) and (67) with acid gives a mixture of the tetraenes (5) and (68). Photo-oxygenation of the latter mixture provides a convenient method for isolating the tetraene (68). Similar reductions of 13-methoxytotara-5,8,11,13-tetraen-7-one (76) have been examined and products from the action of m-chloroperbenzoic acid on the enol acetates (19), (20) and (7) are reported. 
ER  -

