1.1: water; sodium hydroxide / tetrahydrofuran / 0.75 h / 20 °C 2.1: caesium carbonate / methanol / pH 7 2.2: 11 h / 0 - 20 °C / Inert atmosphere 3.1: pyridinium poly(hydrogen fluoride) / tetrahydrofuran / 12 h / 0 - 20 °C 4.1: toluene / 5 h / 60 °C / Inert atmosphere 5.1: 10 Pd(OH)2 on C; hydrogen / methanol / 36 h / 20 °C 6.1: piperidine; 4-(N,N-dimethlyamino)pyridine / N,N-dimethyl-formamide / 192 h / 20 °C / Inert atmosphere View Scheme