to abietane and podocarpane-type terpenoids from labdane diterpenes is reported. The key step is the transformation of β-ketoester 9 into the corresponding O-acetylsalicylate ester 18, via a manganese(III)-based oxidative free-radical cyclization carried out in Ac2O. Utilizing this, the synthesis of the antitumor (+)-7-deoxynimbidiol (5) from (−)-sclareol (11) has been achieved. (+)-Nimbidiol (6) and
Abstract Three newditerpenes, pisiferin, 15-hydroxyferruginol, and O -methyl pisiferic acid have been isolated and the presence of 12-hydroxyabieta-8,11,13-trien-20-al has been confirmed in studies of the leaves of Chamaecyparispisifera . The structure of pisiferin, a phenolic diterpene with a new carbon skeleton, has been determined by chemical degradation. The presence of diterpenes of the ferruginol