Hydrochloric Acid → HCID 10988154, compound

Participants

Reaction Steps

Sodium hydride (2.1 g, 52.4 mmol) was washed with iso-hexane under a nitrogen atmosphere. Tetrahydrofuran (20 ml) was added and the suspension cooled in an ice/water bath. A mixture of N-(tert-butoxycarbonyl)-O-methyl-L-serine (starting material obtained by converting the dicyclohexylamine salt to the free base as described above in the pre-amble to the Examples) (2.5 g, 11.4 mmol) and water (41 μl, 2.28 mmol) in tetrahydrofuran (15 ml) was slowly added. The resulting mixture was allowed to stir for 20 minutes and dimethylsulfate (3.3 ml, 35.3 mmol) was slowly added. The mixture was stirred for 2 hours and treated with concentrated ammonium hydroxide (15 ml). The resulting mixture was stirred for a further 2 hours, then acidified with 2M hydrochloric acid, extracted with ethyl acetate, dried (MgSO4) and concentrated under reduced pressure. The residues were dissolved in methanol, absorbed onto an NH2 column, washed with methanol and eluted with 7N ammonia in methanol. Appropriate fractions were combined and evaporated under reduced pressure to give N-(tert-butoxycarbonyl)-N,O-dimethyl-L-serine (1.5 g, 56%) as a viscous, colourless oil; 1H NMR spectrum: (DMSO d6, 100° C.) 1.40 (s, 9H), 2.77 (s, 3H), 3.26 (s, 3H), 3.67 (m, 2H), 4.51 (m, 1H).

Provenance & Evidence