2-Methyl-3-(5'-norbornen-2'-yl)propenal 2-Propenal, 3-bicyclo(2.2.1)hept-5-en-2-yl-2-methyl- 3-(Bicyclo(2.2.1)hept-5-en-2-yl)methacrylaldehyde 38284-42-3 AI3-24759 EINECS 253-861-1