1: 2,2-Dimethyl-[1,3]dioxane-4,6-dione; cyclopropionyl chloride With pyridine in chloroform T=10 - 20°C; 2 h; 2: methanol 3 h; Heating / reflux;

pyridine in dichloromethane T=0 - 20°C;

1: carbonic acid dimethyl ester With sodium hydride in tetrahydrofuran T=20°C; 2: cyclopropane carboxylic acid cyanide in tetrahydrofuran T=20 - 75°C; 2.16667 h;

1: cyclopropanecarboxylic acid With 1,1'-carbonyldiimidazole in tetrahydrofuran T=0 - 20°C; 60 h; 2: magnesium salt of monomethyl malonic acid in tetrahydrofuran T=20°C; Claisen reaction; 16 h; Further stages.;

1,1'-carbonyldiimidazole; magnesium chloride in tetrahydrofuran

T=20°C; 6 h;

in methanol

1.1: sulfuric acid / water; methanol / 22.25 h / 25 - 65 °C 1.2: 0.75 h / 0 - 25 °C / pH 6 2.1: toluene / 5 h / 25 °C / Inert atmosphere 2.2: 3 h 2.3: 2 h / 40 °C 3.1: potassium carbonate / dimethyl sulfoxide / 7 h / 75 °C 4.1: water; oxalic acid / methanol / 6 h / 35 °C 4.2: 2.75 h / 10 - 30 °C / pH 7 View Scheme

1: potassium tert-butylate / methanol / 23 - 60 °C 2: tetraethylammonium chloride; N,N-dimethyl-aniline; trichlorophosphate / acetonitrile / 0.33 h / 110 °C View Scheme

1.1: sulfuric acid / water; methanol / 22.25 h / 25 - 65 °C 1.2: 0.75 h / 0 - 25 °C / pH 6 2.1: toluene / 5 h / 25 °C / Inert atmosphere 2.2: 3 h 2.3: 2 h / 40 °C 3.1: potassium carbonate / dimethyl sulfoxide / 7 h / 75 °C 4.1: water; oxalic acid / methanol / 6 h / 35 °C 4.2: 2.75 h / 10 - 30 °C / pH 7 5.1: hydrogenchloride; water / methanol / 2.17 h / 25 °C 5.2: 0.92 h / 0 - 25 °C / pH 3 View Scheme