tetrabutyl ammonium fluoride in tetrahydrofuran 20 h; Ambient temperature; Yield given;

1: triethylamine / 1,2-dimethoxy-ethane / 18 h / Ambient temperature 2: HCl (gas) / ethyl acetate / 0.33 h / -25 °C 3: 1-hydroxybenzotriazole (HOBT), 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride (EDC), triethylamine / dimethylformamide / 20 h / Ambient temperature 4: tetrabutylammonium fluoride (TBAF) / tetrahydrofuran / 20 h / Ambient temperature View Scheme

1: 96 percent / 1-hydroxybenzotriazole (HOBT), 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride (EDC) / dimethylformamide / 18 h / Ambient temperature 2: triethylamine / 1,2-dimethoxy-ethane / 18 h / Ambient temperature 3: HCl (gas) / ethyl acetate / 0.33 h / -25 °C 4: 1-hydroxybenzotriazole (HOBT), 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride (EDC), triethylamine / dimethylformamide / 20 h / Ambient temperature 5: tetrabutylammonium fluoride (TBAF) / tetrahydrofuran / 20 h / Ambient temperature View Scheme

1: EDC, HOBt / dimethylformamide / pH = 8.0-9.0 2: tetrabutylammonium fluoride / tetrahydrofuran / 18 h / Ambient temperature View Scheme