The Diels-Alder reaction of 6, 6-dimethylfulvene with 1-acetoxyacrylonitrile gave two different adducts, 2-acetoxy-2-cyano-7, 7-isopropylidenebicyclo [2.2. l] hept-5-ene (3, 70%) and 2-acetoxy-2-cyano-1-isopropenyl-bicyclo [2.2. l] hept-5-ene (4, 18%). The formation of 4, which has not been reported before,. can be suppressed by adding pyridine to the reaction mixture. Hydrolysis of 3 by sodium methoxide, followed by successive treatment with ...