1.1: toluene-4-sulfonic acid / tetrahydrofuran / 12 h / 0 - 20 °C 2.1: n-butyllithium / tetrahydrofuran / 0.07 h / -78 °C / |Inert atmosphere 2.2: -78 - 20 °C / |Inert atmosphere 3.1: 4-(N,N-dimethlyamino)pyridine; pyridine / 20 °C 4.1: AlCl3, aluminium chloride / nitromethane / 0.5 h / 60 °C / |Acidic conditions; |Microwave irradiation View Scheme