1: 1.) s-BuLi, TMEDA / 1.) THF, cyclohexane, -90 deg C, 1 h, 2.) THF, cyclohexane, -80 deg C, 10 min 2: ClSO3H / 1.5 h / 125 °C 3: aq. Na2SO3, aq. NaOH / 3 h / 15 - 20 °C 4: a) aq. NaOH, b) K2CO3 / dimethylformamide / 5 h / Heating View Scheme

1: ClSO3H / 1.5 h / 125 °C 2: aq. Na2SO3, aq. NaOH / 3 h / 15 - 20 °C 3: a) aq. NaOH, b) K2CO3 / dimethylformamide / 5 h / Heating View Scheme

1: aq. Na2SO3, aq. NaOH / 3 h / 15 - 20 °C 2: a) aq. NaOH, b) K2CO3 / dimethylformamide / 5 h / Heating View Scheme

1: 1.) s-BuLi, TMEDA / 1.) THF, cyclohexane, -90 deg C, 1 h, 2.) THF, cyclohexane, -80 deg C, 10 min 2: 1.) s-BuLi, TMEDA / 1.) THF, cyclohexane, -90 deg C, 1 h, 2.) THF, cyclohexane, -80 deg C, 10 min 3: ClSO3H / 1.5 h / 125 °C 4: aq. Na2SO3, aq. NaOH / 3 h / 15 - 20 °C 5: a) aq. NaOH, b) K2CO3 / dimethylformamide / 5 h / Heating View Scheme

sodium hydroxide; potassium carbonate in N,N-dimethyl-formamide 5 h; Heating; Yield given;