Bromobenzene → 4-Benzyl-1-phenylpiperazin-2-one

HRID 1876659Notes

Reaction equation

Br[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[CH2:8]([N:15]1[CH2:20][CH2:19][NH:18][C:17](=[O:21])[CH2:16]1)[C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=1.C(=O)([O-])[O-].[K+].[K+]>[Cu]I>[CH2:8]([N:15]1[CH2:20][CH2:19][N:18]([C:2]2[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=2)[C:17](=[O:21])[CH2:16]1)[C:9]1[CH:10]=[CH:11][CH:12]=[CH:13][CH:14]=1

Participants

Conditions

Temperature: 220 °C

Procedure

To a 25 mL microwave vessel was added 4-bromobenzene (6.1 g, 39.0 mmol), 4-benzylpiperazin-2-one (5.0 g, 36.3 mmol), potassium carbonate (3.6 g, 26.3 mmol), and copper(I) iodide (500 mg, 2.6 mmol). The reaction vessel was sealed and purged with nitrogen. Anhydrous NMP (8.0 mL) was added via syringe. The vessel was heated via microwave at 220° C. for 40 minutes. The mixture was filtered through a bed of celite followed by CH2Cl2 (20 mL). The filtrate was purified via silica gel chromatography using 2% MeOH in CH2Cl2 to obtain the desired piperazinone as a white solid (3.4 g, 12.7 mmol, 50% yield). 1H NMR (400 MHz, CDCl3) δ 7.42-7.24 (m, 10H), 3.69 (t, J=5.4 Hz, 1H), 3.63 (s, 1H), 3.40-3.31 (m, 2H), 2.84 (s, 1H), 2.81 (t, J=5.2 Hz, 1H). LC/MS (10%-99% CH3CN (0.035% TFA)/H2O (0.05% TFA)), m/z: M+1 obs=267.3; tR=1.63 min.

Workup

customThe reaction vessel was sealed
custompurged with nitrogen
additionAnhydrous NMP (8.0 mL) was added via syringe
filtrationThe mixture was filtered through a bed of celite
customThe filtrate was purified via silica gel chromatography

Sources & evidence

ORD record: ord-a949f5adf3874425817dd6ac9f5673c8
Source dataset: uspto-grants-2012_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08309587B2

Reaction notes

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