1.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / dichloromethane / 5 h / 20 °C / |Inert atmosphere 2.1: dicobalt octacarbonyl / hexane / 1 h / |Inert atmosphere 2.2: 20 °C / 4500.45 Torr / |Inert atmosphere; |Molecular sieve 3.1: pyridine hydrogenfluoride / tetrahydrofuran / 0 - 20 °C / |Inert atmosphere 4.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / -78 °C / |Inert atmosphere 4.2: -78 °C / |Inert atmosphere View Scheme