1: tetrabutyl ammonium fluoride; acetic acid 2: 4-(N,N-dimethlyamino)pyridine; dicyclohexyl-carbodiimide / dichloromethane 3: N-ethyl-N,N-diisopropylamine / methanol / 2 h 4: triethylamine tris(hydrogen fluoride) / tetrahydrofuran / 24 h 5: 4 h 6: pH 5 View Scheme