Reaction with Diethyl Malonate.-Diethyl malonate is reactive at the methylene position rather than at a carbonyl group. When this ester was heated with N, N-diniethylisobutenylamine, dimethylamine was evolved and the product obtained on distillation appeared to he mainly diethyl isobutylidenemalonate (9). h second component, shown to be present by vapor phase chromatography, was apparently diethyl isobutenylmalonate (10) since ...