5-Bromo-2-methyl-2-pentene → 3-(4-Methylpent-3-en-1-yl)cyclopent-2-en-1-one

HRID 724502Notes

Reaction equation

HRID 724502 reaction equation
[Mg].Br[CH2:3][CH2:4][CH:5]=[C:6]([CH3:8])[CH3:7].CO[C:11]1[CH2:15][CH2:14][C:13](=[O:16])[CH:12]=1>C(OCC)C>[CH3:7][C:6]([CH3:8])=[CH:5][CH2:4][CH2:3][C:11]1[CH2:15][CH2:14][C:13](=[O:16])[CH:12]=1

Participants

5

Reactant 3

HCID 1375215-Bromo-2-methyl-2-penteneHCID 6434763-Methoxycyclopent-2-en-1-oneHCID 5462224Magnesium

Product 1

HCID 218811443-(4-Methylpent-3-en-1-yl)cyclopent-2-en-1-oneYield 65%

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent2×

Procedure

Magnesium turnings 2.1 g (0.086 mole) were added to 50 ml diethyl ether with stirring. 1-Bromo-4-methyl-3-pentene 10 g (0.061 mole) was added dropwise over 30 minutes. The reaction was allowed to warm from 25° C. to 40° C. during the addition and aged for 30 minutes. A solution of 3-Methoxy-2-cyclopenten-1-one, 10 g (0.089 mole) in diethyl ether was added at 25° C. The resulting mixture was aged 30 minutes then quenched with 20% aqueous acetic acid (50 ml). The organic layer was dried over sodium sulfate, filtered and distilled to give 6.6 g (65% yield) of 3-(4-methyl-3-pentenyl)-2-cyclopenten-1-one. The 3-(4-methyl-3-pentenyl)-2-cyclopenten-1-one had a boiling point (Bp) of 117° C. at 5 mmHg.

Workup

  1. temperatureto warm from 25° C. to 40° C. during the addition
  2. waitThe resulting mixture was aged 30 minutes
  3. customthen quenched with 20% aqueous acetic acid (50 ml)
  4. dry with materialThe organic layer was dried over sodium sulfate
  5. filtrationfiltered
  6. distillationdistilled

Sources & evidence

ORD record
ord-bee2759d276041d7a9175735d6cceb12
Source dataset
uspto-grants-2006_11
Patent number
US07141699B1

Reaction notes

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