2-Methyl-2-(dimethoxymethyl)-7,7-dimethoxy-5-norbornene 2-Methyl-7-oxo-5-norbornene-2-carboxaldehyde bis(dimethyl acetal) 31969-69-4 5-Norbornene-2-carboxaldehyde, 2-methyl-7-oxo-, bis(dimethyl acetal)