1: in toluene 4 h; Heating / reflux; 2: With (2E)-but-2-enedioic acid in acetone T=20°C; 3: With water; sodium hydrogencarbonate in dichloromethane

sodium hydroxide in water; toluene 8 h; Heating / reflux;

potassium 2-methyl-2-butoxide in N,N-dimethyl-formamide; toluene T=55 - 85°C; RefluxLarge scale;

1: triethylamine; formaldehyd / isopropyl alcohol; water / 35 - 45 °C / |Large scale 2: potassium 2-methyl-2-butoxide / toluene; N,N-dimethyl-formamide / 55 - 85 °C / |Reflux; |Large scale View Scheme

1: triphenylphosphine; palladium diacetate; 4-(N,N-dimethlyamino)pyridine / tetrahydrofuran; N,N-dimethyl-formamide / 18 h / 130 °C / 3750.38 - 4500.45 Torr / |Autoclave; |Inert atmosphere; |Large scale 2: hydrogen; 5 Pd/C / methanol / 45 - 55 °C / |Inert atmosphere; |Large scale 3: triethylamine; formaldehyd / isopropyl alcohol; water / 35 - 45 °C / |Large scale 4: potassium 2-methyl-2-butoxide / toluene; N,N-dimethyl-formamide / 55 - 85 °C / |Reflux; |Large scale View Scheme