Benzyl Bromide → Ethyl 3-oxo-5-phenylpentanoate

HRID 3396

Reaction equation

HRID 3396 reaction equation
[H-].[Na+].[C:3]([O:9][CH2:10][CH3:11])(=[O:8])[CH2:4][C:5]([CH3:7])=[O:6].[CH2:12](Br)[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1>CCCCCC.C1COCC1>[CH2:10]([O:9][C:3](=[O:8])[CH2:4][C:5]([CH2:7][CH2:12][C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1)=[O:6])[CH3:11]

Participants

6

Reactant 3

HCID 7498Benzyl BromideHCID 8868Ethyl AcetoacetateHCID 24758Sodium hydride

Product 1

HCID 61162Ethyl 3-oxo-5-phenylpentanoate

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolvent2×HCID 8058HexaneSolvent

Conditions

Temperature
-10 °C

Procedure

NaH (13.8 g, 0.6 mole) was washed twice with hexane (2×50 ml) and suspended in 250 ml of freshly distilled THF. Next ethyl acetoacetate (75 ml, excess) was added dropwise carefully while the receiving flask was cooled at -10° C. After the addition was complete, it was stirred at -10° C. for 2 hours and at room temperature for 30 min. Benzylbromide (51.0 g, 0.3 mole) in THF was added dropwise at room temperature to the above solution. The reaction mixture was stirred overnight at room temperature. The reaction was terminated the next day by pouring into ice cold water, brought to neutral pH, and extracted with ether/ethylacetate. The combined ether/ethylacetate extracts were rinsed over brine and dried over Na2SO4. Removal of the solvent followed by careful vacuum distillation gave ethyl-benzylacetoacetate, bp 276° C. IR: (neat), cm-1 : 2900-3050, 1690-1760 (broad), 1655. NMR (CDCl3):δ:1.25 (t1 3H, CH2CH3); 2.25 (s, 3H, COCH3); 3.20 (d, 2H, benzylic CH2); 3.8 (t, 1H, COCHCO); 4.20 (q, 2H, OCH2CH3); 7.15-7.35 (m, 5H, Ar-H).

Workup

  1. additionAfter the addition
  2. stirringThe reaction mixture was stirred overnight at room temperature
  3. customThe reaction was terminated the next day
  4. additionby pouring into ice cold water
  5. extractionextracted with ether/ethylacetate
  6. washThe combined ether/ethylacetate extracts were rinsed over brine
  7. dry with materialdried over Na2SO4
  8. customRemoval of the solvent
  9. distillationfollowed by careful vacuum distillation

Sources & evidence

ORD record
ord-123a12fd08654e45b37f1f604736d38c
Source dataset
uspto-grants-1998_03
Patent number
US05733934

Linked notes

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