Chemistry of the Podocarpaceae. XXXV. 12-Methoxypodocarpa-8,11,13- triene and 12-Methoxyabieta-8,11,13-triene derivatives: A synthesis of (+)-hinokione methyl ether

12-Methoxypodocarpa-8,11,13-trien-19-oic acid (9) and 12-methoxyabieta- 8,11,13-trien-19-oic acid (10) have been converted into 3-0x0-4,4-dimethyl derivatives (15) and (18) by successive reactions involving oxidative decarboxylation, selective epoxidation, epoxide opening, double bond isomerization, oxidation, and reductive methylation. The sequence starting from the acid (10) provides a synthesis of the methyl ether of hinokione (14).