1: ethyl 2,5-dimethyl-4-formyl-1H-pyrrole-3-carboxylate With potassium tert-butylate in dimethyl sulfoxide 1 h; 2: methyl iodide in dimethyl sulfoxide T=60°C; 2 h;

sodium hydroxide; tetrabutylammomium bromide in dichloromethane T=0°C; 3 h; Yield given;

1.1: POCl3 / 0.5 h / 0 °C 1.2: 1,2-dichloro-ethane / 0.75 h / Heating 1.3: 87 percent / aq. NaOAc*3H2O / 1,2-dichloro-ethane / 0.5 h / Heating 2.1: tBuOK / dimethylsulfoxide / 1 h 2.2: 80 percent / dimethylsulfoxide / 2 h / 60 °C View Scheme

hydrogenchloride; diethyl ether Erwaermen des Reaktionsprodukts mit Wasser;

hydrazine hydrate in ethanol Heating;

1: 83 percent / hydrazine hydrate / ethanol / Heating 2: 71 percent / POCl3 / 4 h / 85 °C View Scheme