Pyridine → tert-butyl 1,3-dioxotetrahydro-1H-oxazolo[3,4-a]pyrazine-7(3H)-carboxylate
Reaction equation
N1C=CC=CC=1.CN(C=O)C.S(Cl)(Cl)=O.C(O[C:21]([N:23]1[CH2:28][CH2:27][N:26]([C:29]([O:31][C:32]([CH3:35])([CH3:34])[CH3:33])=[O:30])[CH2:25][CH:24]1[C:36]([OH:38])=[O:37])=[O:22])(C)(C)C>C1COCC1.CCOC(C)=O.O>[O:37]=[C:36]1[CH:24]2[CH2:25][N:26]([C:29]([O:31][C:32]([CH3:33])([CH3:34])[CH3:35])=[O:30])[CH2:27][CH2:28][N:23]2[C:21](=[O:22])[O:38]1Participants
Reactant 4
Product 1
Reagents, catalysts & solvents 3
Conditions
- Temperature
- 40 °C
Procedure
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.
Workup
- customThe layers were separated
- extractionthe aqueous layer was extracted with EtOAc (2×50 mL)
- dry with materialThe combined extracts were dried over Na2SO4
- filtrationfiltered
- concentrationconcentrated under reduced pressure
- temperaturecooled to −20° C. for 1 h
- filtrationThe solid was collected by filtration
- washwashed with Et2O (2×10 mL)
- customair-dried
Sources & evidence
- ORD record
- ord-eeeac301f6c84c269532d55f0d6cbe5e
- Source dataset
- uspto-grants-2016_08
- Patent number
- US09428522B2
Reaction notes
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