2-Amino-2-methyl-1-propanol → (2R,3R)-2-(3-chlorophenyl)-3,5,5-trimethyl-2-morpholinol

Participants

Reaction Conditions

Reaction Steps

Following the procedure described for (2S,3S)-4a, a sample of (S)-1-(3-Chlorophenyl)-2-hydroxypropan-1-one ((S)-10a, 4.5 g, 0.024 mol), was dissolved in CH2Cl2 (75 mL) and treated with Proton sponge (6.3 g) and cooled to −50° C. Next, triflic anhydride (4.5 mL, 32 mmol) was added slowly, and the reaction mixture was stirred at 0° C. for an additional hour. The resulting orange slurry was transferred by syringe to another flask containing a solution of 2-amino-2-methyl-1-propanol, (4.7 g, 0.052 mol) in CH3CN. After purification, 3.3 g (78%) of the (2R,3R)-4a was isolated and converted to 2.7 g of the Hemi-L-tartrate salt (>99% ee): mp 128-131° C.; [α]23D −13.0° (c 0.79, CH3OH). Characterization data is similar to data reported in Fang, Q. K. et al., Tetrahedron: Asymmetry 2000, 11, 3659-3663.

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