Pyridine → tert-butyl 1,3-dioxotetrahydro-1H-oxazolo[3,4-a]pyrazine-7(3H)-carboxylate

Participants

Reaction Conditions

Reaction Steps

Pyridine (1.4 mL, 17 mmol), DMF (0.29 mL, 3.7 mmol), and thionyl chloride (1.1 mL, 15 mmol) were added in succession to a suspension of 1,4-bis(tert-butoxycarbonyl)piperazine-2-carboxylic acid (3.73 g, 11.3 mmol) in THF (20 mL). The reaction mixture was heated to 40° C. for 3 h. The reaction mixture was diluted with EtOAc (50 mL) and H2O (50 mL). The layers were separated, and the aqueous layer was extracted with EtOAc (2×50 mL). The combined extracts were dried over Na2SO4, filtered, and concentrated under reduced pressure. The material was suspended in Et2O (10 mL) and cooled to −20° C. for 1 h. The solid was collected by filtration, washed with Et2O (2×10 mL), and air-dried. This gave 1.73 g (60%) of the title compound as a white solid.

Provenance & Evidence