Ethyl chloroformate → (1,1-dimethylethyl)tetrahydro-3-oxo-1,1-diphenyl-3H-oxazolo[3,4-a]pyrazine-7(1H)-carboxylate

HRID 1713515Notes

Reaction equation

[CH3:1][C:2]([O:5][C:6]([N:8]1[CH2:13][CH2:12][NH:11][CH:10]([C:14]([OH:27])([C:21]2[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=2)[C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)[CH2:9]1)=[O:7])([CH3:4])[CH3:3].[C:28](=O)([O-])[O-:29].[K+].[K+].C(Cl)(=O)OCC>CN(C)C=O>[CH3:4][C:2]([O:5][C:6]([N:8]1[CH2:13][CH2:12][N:11]2[C:28](=[O:29])[O:27][C:14]([C:15]3[CH:16]=[CH:17][CH:18]=[CH:19][CH:20]=3)([C:21]3[CH:22]=[CH:23][CH:24]=[CH:25][CH:26]=3)[CH:10]2[CH2:9]1)=[O:7])([CH3:1])[CH3:3]

Participants

Conditions

Temperature: 50 °C

Procedure

To a solution of (1,1-dimethylethyl)3-(hydroxydiphenylmethyl)-1-piperazine carboxylate (9.6 g, 26 mmol) in N,N-dimethylformamide (180 mL) were added potassium carbonate (20 g, 0.14 mol) and ethyl chlorocarbonate (14 g, 0.26 mol), and the mixture was stirred at 50° C. for 16 hours. To the reaction solution were further added potassium carbonate (20 g, 0.14 mol) and ethyl chlorocarbonate (14 g, 0.26 mol), and the mixture was further stirred at 50° C. for 18 hours. To the reaction solution was added ice water, and the mixture was extracted with ethyl acetate. The extract was washed with water and concentrated under reduced pressure. The residue was purified with silica gel column chromatography (hexane:ethyl acetate=3:1) to obtain the title compound (6.9 g, yield 64%) as a solid.

Workup

stirringthe mixture was further stirred at 50° C. for 18 hours
extractionthe mixture was extracted with ethyl acetate
washThe extract was washed with water
concentrationconcentrated under reduced pressure
customThe residue was purified with silica gel column chromatography (hexane:ethyl acetate=3:1)

Sources & evidence

ORD record: ord-c1ae8d3580a44c009ca964272cf74748
Source dataset: uspto-grants-2010_09
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07795267B2

Reaction notes

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