1: di-isopropyl ether / 2 h / -10 - 0 °C / |Large scale 2: O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate; N-ethyl-N,N-diisopropylamine / dichloromethane / 2 h / 0 - 20 °C / |Large scale 3: hydrogenchloride / toluene / 1 h / 0 °C / |Large scale 4: O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate; N-ethyl-N,N-diisopropylamine / dichloromethane / 2 h / 0 - 20 °C / |Large scale 5: hydrogenchloride; 2-methylpropylboronic acid / hexane; MeOD-d4; water / 0 - 20 °C / |Large scale View Scheme