Constituents of Solidago Species. Part III. The Constitution of Diterpenoids from Solidago juncea Ait

The constitution and stereochemistry of five new diterpenoids from Solidago juncea Ait., junceic acid ( 3 a), the related epoxide ( 6 a), junceanol W( 4 a), junceanol X ( 4 b), and junceanol Y ( 5 a), have been assigned on the basis of their chemical and spectroscopic properties. Of key importance in these deductions have been the transformations of 4 b and 5 a into the previously described hydrocarbon 19 and of 3 a into 3 e. Two known diterpenoids, (−)-hardwickiic acid ( 2 a), which has also been converted into 3 e, and ent-16-kauren-19-oic acid ( 1 ), are further constituents of S. juncea.