1.1: iso-propylmagnesium bromide / tetrahydrofuran / 14 h / -10 - 20 °C / Inert atmosphere 1.2: 2 h / -10 °C 2.1: sodium tetrahydroborate; boron trifluoride diethyl etherate / tetrahydrofuran / 2 h / -10 - 20 °C 2.2: 1 h / 0 - 40 °C 2.3: 12 h View Scheme