1.1: lithium hexamethyldisilazane / tetrahydrofuran; hexane / 2 h / -78 °C 1.2: 2 h / 20 °C 2.1: thionyl chloride / N,N-dimethyl-formamide / tetrahydrofuran / 1 h / 20 °C 3.1: triethylamine / tetrahydrofuran; DMF (N,N-dimethyl-formamide) / 16 h / 0 - 20 °C View Scheme