toluene-4-sulfonic acid 18 h; Ambient temperature;

zinc(II) chloride in acetonitrile 1 h; Ambient temperature; Yield given. Yields of byproduct given;

1: 1.) mercuric acetate; 2.) 3M sodium hydroxide, sodium borohydride / 1.) water, THF, 30 min, 2.) water, 10 min, 0 deg C 2: 81 percent / p-toluenesulfonic acid monohydrate / 18 h / Ambient temperature View Scheme