1: pyridine / dichloromethane / 0 - 20 °C 2: tetrahydrofuran; diethyl ether / 2 h / -75 °C 3: hydrogenchloride / water; 1,3,5-trimethyl-benzene / 1 h / |Reflux 4: sodium methylate / tetrahydrofuran; methanol / 6 h / 20 °C View Scheme