Sodium borohydride → (2S)-4-methyl-2-(isobutylamino)pentanol

To a solution of (4 g)-2-isopropyl-4-isobutyl-1,3-oxazolidine (223g, 1.3 mol) in EtOH (1.1 L) cooled to −13° C. with an ice/MeOH bath was added NaBH4 (70.3 g, 1.82 mol) in portions at such a rate that the reaction temp. did not exceed 10° C. (approximately 2 h). The reaction mixture was allowed to warm to room temp., stirred overnight, then filtered through a coarse sintered glass funnel. The resulting solids were washed with EtOH. The combined filtrate was concentrated under reduced pressure and the residue was treated with EtOAc (2 L) and water (1 L). The organic layer was dried (Na2SO4) and concentrated under reduced pressure to yield (2S)-4-methyl-2-(isobutylamino)pentan-1-ol as a viscous pale yellow oil (192 g, 85%): 1H NMR (CDCl3) δ0.90-0.96 (m, 12H), 1.18-1.24 (m, 1H), 1.32-1.39 (m, 1H), 1.58-1.72 (m, 2H), 2.33 (dd, J=11.1, 7.0 Hz, 1H), 2.49 (dd, J=11.1, 7.0 Hz, 1H), 2.61-1.67 (m, 1H), 3.19 (dd, J=10.3, 6.2 Hz, 1H), 3.60 (dd, J=10.3, 6.2 Hz, 1H).