methanesulfonyl chloride; triethylamine in dichloromethane T=0°C; 2 h;

in xylene 50 h; Heating;

1: 60percent aq. AcOH / Ambient temperature 2: 70 percent / DMSO, oxalyl chloride, Et3N / CH2Cl2 / 0.83 h / -60 °C 3: 45 percent / BF3*OEt2 / CH2Cl2 / 9 h / Ambient temperature 4: 96 percent / mesyl chloride, Et3N / CH2Cl2 / 2 h / 0 °C View Scheme

1: 60percent aq. AcOH / Ambient temperature 2: 70 percent / DMSO, oxalyl chloride, Et3N / CH2Cl2 / 0.83 h / -60 °C 3: 45 percent / BF3*OEt2 / CH2Cl2 / 9 h / Ambient temperature 4: 96 percent / mesyl chloride, Et3N / CH2Cl2 / 2 h / 0 °C View Scheme

in 1,2-dichloro-benzene 72 h; Inert atmosphereReflux;

in xylene 60 h; Heating;