Ethyl Acetate → Bis(1,2-dimethylpropyl)borane

HRID 1292413Notes

Reaction equation

HRID 1292413 reaction equation
[BH3:1].[CH2:2]1[CH2:6]O[CH2:4][CH2:3]1.[CH3:7][C:8](=[CH:10][CH3:11])[CH3:9].[Cl-].[NH4+].[CH3:14]COC(C)=O>C1COCC1>[CH:3]([BH:1][CH:10]([CH:8]([CH3:9])[CH3:7])[CH3:11])([CH:2]([CH3:6])[CH3:14])[CH3:4]

Participants

6

Reactant 4

HCID 8857Ethyl AcetateHCID 105532-Methyl-2-buteneHCID 25517Ammonium ChlorideHCID 2723981Borane;tetrahydrofuran

Product 1

HCID 192733Bis(1,2-dimethylpropyl)borane

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Conditions

Temperature
0 °C

Procedure

A solution of disiamylborane was prepared by mixing 35 mL of BH3THF (1 M in THF) and 35 mL of 2-methyl-2-butene (2 M in THF) at 0° C. followed stirring at 0° C. for 75 minutes. To this solution was introduced 2R-carboethoxy-5-oxotetrahydrofuran dissolved in THF (6 mL). The resultant mixture was allowed to warm slowly to room temperature over a period of 2.5 hours and then was stirred for another 15 hours. Saturated ammonium chloride solution was added, followed by dilution with EtOAc. The above mixture was stirred for 10 minutes and then was transferred to a separatory funnel. The organic phase was washed successively with saturated NH4Cl, brine, and then was dried (Na2SO4). The solvent was removed on a rotary evaporator and the crude product obtained was purified by column chromatography (40% EtOAc-Hexanes). The desired products were isolated in 70% yield (2.05 g) as a 2:3 mixture of isomer epimeric at C5. Trace amount of the open form isomer was also detected (1H NMR). The title compounds displayed the following spectral characteristics: 1H NMR (CDCl3): 6 1.28 (t, 2H, J=7.1 Hz), 1.30 (t, 1H, J=7.1 Hz), 1.85-2.70 (m, 4H), 2.59 -(d, 0.33H, J=5.5 Hz), 2.88 (d, 0.67H, J=3.1 Hz), 4.154.65 (m, 2H), 4.57 (d of d, 0.33H, J=6.4, 8.3 Hz), 4.70 (d of d, 0.67H, J=4.1, 8.7 Hz), 5.59 (m, 0.33H), 5.74 (m, 0.67H).

Workup

  1. temperatureto warm slowly to room temperature over a period of 2.5 hours
  2. stirringwas stirred for another 15 hours
  3. stirringThe above mixture was stirred for 10 minutes
  4. customwas transferred to a separatory funnel
  5. washThe organic phase was washed successively with saturated NH4Cl, brine
  6. dry with materialwas dried (Na2SO4)
  7. customThe solvent was removed on a rotary evaporator
  8. customthe crude product obtained

Sources & evidence

ORD record
ord-a4be2ccebd354594ab69f556f6eee3a5
Source dataset
uspto-grants-1998_05
Patent number
US05756706

Reaction notes

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