Ethyl Acetate → (2S, 6R)-2,6-Dimethyl-3-oxo-piperazine-1-carboxylic acid benzyl ester

HRID 1432907Notes

Reaction equation

[CH2:1]([O:8][C:9]([N:11]1[C@H:16]([CH3:17])[CH2:15][N:14](CC2C=CC(OC)=CC=2OC)[C:13](=[O:29])[C@@H:12]1[CH3:30])=[O:10])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.S(OOS([O-])(=O)=O)([O-])(=O)=O.[K+].[K+].P([O-])([O-])([O-])=O.[Na+].[Na+].[Na+].C(OCC)(=O)C>C(#N)C.O>[CH2:1]([O:8][C:9]([N:11]1[C@H:16]([CH3:17])[CH2:15][NH:14][C:13](=[O:29])[C@@H:12]1[CH3:30])=[O:10])[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1

Participants

Conditions

Temperature: 97.5 °C

Procedure

(2S,6R)-4-(2,4-Dimethoxy-benzyl)-2,6-dimethyl-3-oxo-piperazine-1-carboxylic acid benzyl ester (1.13 g, 2.74 mmol) is dissolved in 20 mL of acetonitrile. An aqueous solution of potassium persulfate (2.2 g, 8.23 mmol) and sodium phosphate (2.3 g, 16.5 mmol) in 12 mL of H2O is added, and the resulting mixture is heated to 95-100° C. for two hours. After cooling to room temperature, ethyl acetate (200 mL) is used to extract the aqueous layer and dried over magnesium sulfate. The residue after filtration and concentration is chromatographed (SiO2, 60% ethyl acetate/hexane) to give (2S, 6R)-2,6-Dimethyl-3-oxo-piperazine-1-carboxylic acid benzyl ester (480 mg, 67% yield) as a yellow oil.

Workup

temperatureAfter cooling to room temperature
extractionto extract the aqueous layer
dry with materialdried over magnesium sulfate
filtrationThe residue after filtration and concentration
customis chromatographed (SiO2, 60% ethyl acetate/hexane)

Sources & evidence

ORD record: ord-cc1b5fd97a134c39b00a8eac1afe0fae
Source dataset: uspto-grants-2009_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07612075B2

Reaction notes

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