1: 1.) HCO2H, PhOMe, HS-(CH2)2-SH, 2.) HCl 2: 1) N-methylmorpholine, 1-β-naphthalenesulphonyloxybenzotriazole / 1) EtOAc, DMF, 1.5h, 2) RT, 12h 3: 1.) HCO2H, PhOMe, HS-(CH2)2-SH, 2.) HCl 4: 1) 1-β-naphthalenesulphonyloxybenzotriazole, 2) N-methylmorpholine / 1) EtOAc, 1.5h, DMF, RT, 2) RT, 15h 5: 92.23 percent / 2N NaOH / methanol; H2O / 1 h / Ambient temperature 6: 10percentHCl, C6H5OCH3, HS-(CH2)2-SH / dioxane / 1 h / Ambient temperature View Scheme