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

HRID 984915Notes

Reaction equation

HRID 984915 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-eb8bcd591af04698aa35bd3f56902caf
Source dataset
uspto-grants-2005_03
Patent number
US06869943B2

Reaction notes

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