1: 16 percent / acetic acid / Ambient temperature 2: 1.) dithiothreitol, 0.1 M EDTA, 2.) aq. NaOH / 1.) pH 7.8, MeOH, 2.) MeOH, room temperature View Scheme

sodium hydroxide; ethylenediaminetetraacetic acid; DL-threo-1,4-dimercapto-2,3-butanediol 1.) pH 7.8, MeOH, 2.) MeOH, room temperature; Yield given. Multistep reaction;