Structurally specific syntheses of isomerically pure 6-substituted bicyclo [2.2. l] hept-5-en-2- one ketals were explored. A conversion of the Diels-Alder adduct of itaconic anhydride with cyclopenta-1, 3-diene into a ketal of 6-methylbicyclo [2.2. l] hept-5-en-2-one was