The oxidation of certain Diels-Alder adducts of levopimaric acid was investigated with a view to preparing intermediates suitable for the synthesis of polycyclic molecules. Oxidation proceeded satisfactorily only in the presence of a 1a-4a double bond. Because of its accessibility the adduct of levopimaric acid and acetylenedicarboxylic ester was used as model for studying the oxidative transformations of such compounds and was found to undergo a number of unusual reactions. © 1969, American Chemical Society. All rights reserved.