methanesulfonyl chloride; triethylamine in toluene T=60°C; 0.5 h;

1: 1.) n-BuLi / 1.) n-hexane, THF, Et2O, -78 deg C, 1 h, 2.) n-hexane, THF, Et2O, RT, 16 h 2: 81 percent / TsCl, pyridine / CH2Cl2 / 58 h / Ambient temperature View Scheme

1: 1.) n-BuLi / 1.) n-hexane, THF, Et2O, -78 deg C, 1 h, 2.) n-hexane, THF, Et2O, RT, 16 h 2: 81 percent / TsCl, pyridine / CH2Cl2 / 58 h / Ambient temperature View Scheme

sodium hydroxide in ethanol 20 h; Heating;