Benzylethanolamine → (R)-2-hydroxymethylmorpholine p-nitrobenzoate

Participants

Reaction Conditions

Reaction Steps

To a mixture of N-benzylethanolamine (302.4 g, 2.0 mol), 2-propanol (185 ml) and water (185 ml) was added dropwise at 15 to 25° C. (S)-epichlorohydrin (185.0 g, 2.0 mol, 99% ee). After reaction at 15 to 25° C. for 7 hr, aqueous 24% NaOH solution (NET 104 g, 2.6 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 (555 ml) and, after partitioning, the organic layer was concentrated under reduced pressure to give a mixture of N-benzyl-2-hydroxymethylmorpholine, N-benzyl-1,4-oxazepane and other byproducts (410.4 g, N-benzyl-2-hydroxymethylmorpholine:N-benzyl-1,4-oxazepane compound=75.2:24.8). To this mixture were added methanol (830 ml) and palladium carbon (40.0 g when dry), and the mixture was reacted under a hydrogen stream at 25° C. for 15 hr. Palladium carbon was filtered off, methanol was evaporated under reduced pressure to give a mixture of 2-hydroxymethylmorpholine and a 1,4-oxazepane compound (265.7 g, 2-hydroxymethylmorpholine:1,4-oxazepane compound=75.8:24.2). To the mixture (20.0 g) were added methanol (100 ml) and p-nitrobenzoic acid (25.2 g, 0.151 mol) and the mixture was stirred for 30 min. Then, methanol was evaporated under reduced pressure. To the residue was added 2-propanol (50 ml) and the mixture was subjected twice to azeotropic distillation with dehydrating. To the residue after azeotropic distillation with dehydrating was added ethyl acetate (100 ml) at 40° C., and the mixture was cooled to 10° C. 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 (25 ml) and dried (1 mmHg, 40° C.) to give (R)-2-hydroxymethylmorpholine p-nitrobenzoate (17.7 g) (yield from (S)-epichlorohydrin 41.3%). The obtained (R)-2-hydroxymethylmorpholine p-nitrobenzoate was analyzed by HPLC to find an optical purity of 99% ee.

Provenance & Evidence