1: diethyl malonate With sodium hydride in N,N-dimethyl-formamide; mineral oil T=0°C; 1 h; Inert atmosphere; 2: 3-bromo propionaldehyde dimethyl acetal With tetra-(n-butyl)ammonium iodide in N,N-dimethyl-formamide; mineral oil T=100°C; 12 h; Inert atmosphere;

perchloric acid in methanol T=35 - 40°C; 0.5 h;

1: sodium carbonate; N-benzyl-N,N,N-triethylammonium chloride / toluene / 12 h / 40 - 45 °C 2: perchloric acid / methanol / 0.5 h / 35 - 40 °C View Scheme

1: With sodium hydride in tetrahydrofuran 2: With toluene-4-sulfonic acid in acetone

1: diethyl 2-(3,3-dimethoxypropyl)malonate With sodium hydride in tetrahydrofuran T=0 - 20°C; 2: ethylene dibromide in tetrahydrofuran 36 h; Heating;

1.1: NaH / tetrahydrofuran / 0 - 20 °C 1.2: 51 percent / tetrahydrofuran / 36 h / Heating 2.1: 68 percent / aq. p-toluenesulfonic acid / acetone / 2 h / Heating View Scheme