1: 2,4,6-triisopropylbenzenesulfonyl chloride, pyridine / 1.) 25 deg C, 2.) room temperature, overnight 2: 2 M NaOH / 3 h / 25 °C View Scheme

1: pyridine 2: pyridine / 24 h 3: 80percent aq. HCOOH / 4.5 h 4: 2,4,6-triisopropylbenzenesulfonyl chloride, pyridine / 1.) 25 deg C, 2.) room temperature, overnight 5: 2 M NaOH / 3 h / 25 °C View Scheme