(S)-1-[(S)-1-(2,6-difluoropyridin-3-yl)ethylamino]propan-2-ol (+)-di-p-toluoyl-D-tartrate → (S)-4-[(S)-1-(2,6-difluoropyridin-3-yl)ethyl]-6-methylmorpholine-2,3-dione

Participants

Reaction Conditions

Reaction Steps

(S)-1-[(S)-1-(2,6-difluoropyridin-3-yl)ethylamino]propan-2-ol (+)-di-p-toluoyl-D-tartrate (199 g) was dissolved in 5 N aqueous sodium hydroxide (450 mL), water (1,000 mL), and 50% toluene-THF (2,000 mL), and the organic layer was separated. The aqueous layer was washed with 50% toluene-THF (800 mL) three times. The organic layers were combined and concentrated under reduced pressure. Then, diethyl oxalate (200 mL) was added to the residue, and the reaction solution was heated and stirred at 140 to 150° C. Three hours later, the reaction solution was diluted with toluene (500 mL) and then ice-cooled while stirring. The precipitated crystals were collected by filtration, washed with toluene and diethyl ether, and then air-dried to obtain 103 g of the title compound.

Provenance & Evidence