Benzyl 3-oxopiperazine-1-carboxylate → 5-Ethoxy-3,6-dihydro-2H-pyrazine-1-carboxylic acid benzyl ester

HRID 394537Notes

Reaction equation

HRID 394537 reaction equation
[CH2:1]([O:8][C:9]([N:11]1[CH2:16][CH2:15][NH:14][C:13](=[O:17])[CH2:12]1)=[O:10])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.F[B-](F)(F)F.[CH2:23]([O+](CC)CC)[CH3:24]>ClCCl>[CH2:1]([O:8][C:9]([N:11]1[CH2:12][C:13]([O:17][CH2:23][CH3:24])=[N:14][CH2:15][CH2:16]1)=[O:10])[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1

Participants

4

Reactant 2

HCID 736777Benzyl 3-oxopiperazine-1-carboxylateHCID 2723982Triethyloxonium tetrafluoroborate

Product 1

HCID 542316815-Ethoxy-3,6-dihydro-2H-pyrazine-1-carboxylic acid benzyl esterYield 95%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To a solution of 3-oxo-piperazine-1-carboxylic acid benzyl ester (2.0 g, 8.54 mmol, Maybridge) in dichloromethane (18 mL) at room temperature was added triethyloxonium tetrafluoroborate (4.1 g, 21.3 mmol). This mixture was allowed to stir for about 3 days then quenched by the addition of ice chips followed by saturated aqueous sodium bicarbonate until a neutral pH was obtained. The organic layer was separated and the aqueous layer was extracted with chloroform (3×). The combined organic extracts were washed with brine (1×), dried over sodium sulfate, and concentrated to give 2.11 g (95%) of the title compound of Example 259, Step A as a slightly yellow oil that was sufficiently pure to carry on to the next step. 1H NMR (CDCl3, 300 MHz) δ 7.43-6.97 (c, 5H), 5.17 (s, 2H), 4.10 (q, 2H), 3.98 (s, 2H), 3.60-3.40 (c, 4H), 1.27 (t, 3H); MS (APCI) 263 (MH+).

Workup

  1. customthen quenched by the addition of ice chips
  2. customwas obtained
  3. customThe organic layer was separated
  4. extractionthe aqueous layer was extracted with chloroform (3×)
  5. washThe combined organic extracts were washed with brine (1×)
  6. dry with materialdried over sodium sulfate
  7. concentrationconcentrated

Sources & evidence

ORD record
ord-d884e7109bdd44abae4c2de4bab70bf8
Source dataset
uspto-grants-2003_08
Patent number
US06602875B2

Reaction notes

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