1.1: potassium carbonate / N,N-dimethyl-formamide / 1 h / 50 °C 1.2: 5 h / 75 °C 2.1: water; sodium hydroxide / tert-butyl methyl ether / 20 °C 3.1: benzenesulfonyl chloride; triethylamine / tert-butyl methyl ether; toluene / 2 h / 80 °C 3.2: 50 °C View Scheme