1.1: sodium hydroxide; water / methanol / 2 h / 20 °C 1.2: pH 5.5 2.1: N-ethyl-N,N-diisopropylamine; O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate / dichloromethane / 12 h 3.1: sodium tetrahydroborate; boron trifluoride diethyl etherate / tetrahydrofuran / 2 h / -10 - 20 °C 3.2: 1 h / 0 - 40 °C 3.3: 12 h View Scheme