Benzylethanolamine → (R)-Morpholin-2-ylmethanol 2,2,2-trifluoroacetate salt

Participants

Reaction Conditions

Reaction Steps

To a mixture of N-benzylethanolamine (81.7 g, 0.540 mol), 2-propanol (50 ml) and water (50 ml) was added dropwise at 15 to 25° C. (S)-epichlorohydrin (50.0 g, 0.540 mol, 99% ee). After reaction at 10 to 25° C. for 7 hr, aqueous 24% NaOH solution (NET 28.1 g, 0.703 mol) was added at 5 to 10° C. After reaction at 25° C. for 20 hr, the reaction mixture was concentrated under reduced pressure to evaporate 2-propanol. To the residue was added toluene (150 ml) and, after partitioning, the organic layer was concentrated under reduced pressure. The residue was distilled (0.5 mmHg, 150 to 180° C.) to give a mixture of N-benzyl-2-hydroxymethylmorpholine and N-benzyl-1,4-oxazepane compound (76.3 g, N-benzyl-2-hydroxymethylmorpholine:N-benzyl-1,4-oxazepane compound=76.5:23.5). To this mixture were added methanol (153 ml), trifluoroacetic acid (44.1 g, 0.387 mol) and palladium carbon (15.3 g when dry), and the mixture was reacted under a hydrogen stream at 25° C. for 15 hr. Palladium carbon was filtered off, and the filtrate was concentrated under reduced pressure. The residue was subjected twice to azeotropic distillation with dehydrating with 2-propanol (76 ml). To the residue after azeotropic distillation with dehydrating was added ethyl acetate (382 ml) at 40° C., and the mixture was cooled to 20° C. Seed crystal was added and, after crystallization, the mixture was cooled to 0° C. and stirred for 1 hr. The crystals were collected by filtration, washed withed twice with ethyl acetate (76 ml) and dried (1 mmHg, 40° C.) to give (R)-2-hydroxymethylmorpholine trifluoroacetate (50.22 g) (yield from (S)-epichlorohydrin: 40.2%). The obtained (R)-2-hydroxymethylmorpholine trifluoroacetate was analyzed by HPLC to find an optical purity of 99% ee.

Provenance & Evidence