Dibromomethane → (S)-2-methyl-4-methylidene-3-(2-propynyl)cyclopent-2-ene-1-ol

HRID 1079006Notes

Reaction equation

HRID 1079006 reaction equation
BrCBr.O1CCC[CH2:5]1.[OH:9][C@H:10]1[CH2:14][C:13](=O)[C:12]([CH2:16][C:17]#[CH:18])=[C:11]1[CH3:19].C(=O)(O)[O-].[Na+]>ClCCl.[Zn].[Ti](Cl)(Cl)(Cl)Cl.O.CCCCCC>[CH3:19][C:11]1[C@@H:10]([OH:9])[CH2:14][C:13](=[CH2:5])[C:12]=1[CH2:16][C:17]#[CH:18]

Participants

10

Reactant 4

HCID 3024DibromomethaneHCID 8028Tetrahydrofuran2×HCID 1569974-Hydroxy-3-methyl-2-(prop-2-yn-1-yl)cyclopent-2-en-1-oneHCID 516892Sodium Bicarbonate

Product 1

HCID 11829602(S)-2-methyl-4-methylidene-3-(2-propynyl)cyclopent-2-ene-1-olYield 2.6%

Reagents, catalysts & solvents 5

HCID 23994ZincCatalystHCID 24193Titanium TetrachlorideCatalystHCID 962WaterSolventHCID 6344DichloromethaneSolvent2×HCID 8058HexaneSolvent

Procedure

Dibromomethane (1.3 g) and zinc dust (1.5 g) were added to dry tetrahydrofuran (20ml), and the resulting mixture was cooled to 0°~5° C. A dichloromethane solution (5 ml) of 1M titanium tetrachloride was added to the tetrahydrofuran solution over about 10 min, and the resulting mixture was allowed to react for 3 days at 0°5° C. Then a solution of (S)-4-hydroxy-3-methyl-2-(2-propynyl)cyclopent-2-ene-1-one (675 mg) in dichloromethane (10 ml) was added at 0°~5° C. over about 10 min. After the resulting mixture was allowed to react for 2 hours at the same temperature, hexane (40 ml) and then a slurry consisting of sodium bicarbonate (8 g) and water (4 ml) were added. After stirring for 2 hours at 0°~5° C., the organic layer was separated by decantation. The obtained residue was extracted three times with n-hexane (20 ml). The combined organic layer was washed with saturated aqueous sodium bicarbonate solution, and dried over anhydrous magnesium sulfate. Then the solvent was evaporated under reduced pressure, and the resultant residue was subjected to silica gel column chromatography (eluent; n-hexane: ethyl acetate=3:1) to afford the desired product, (S)-2-methyl-4-methylidene-3-(2-propynyl)cyclopent-2-ene-1-ol (17 mg, yield 2.6% as a pale yellow oil.

Workup

  1. temperaturethe resulting mixture was cooled to 0°~5° C
  2. customto react for 3 days at 0°5° C
  3. additionwere added
  4. customthe organic layer was separated by decantation
  5. extractionThe obtained residue was extracted three times with n-hexane (20 ml)
  6. washThe combined organic layer was washed with saturated aqueous sodium bicarbonate solution
  7. dry with materialdried over anhydrous magnesium sulfate
  8. customThen the solvent was evaporated under reduced pressure

Sources & evidence

ORD record
ord-130f5da5bcd94b1f9e3441a8087c48e9
Source dataset
uspto-grants-1996_08
Patent number
US05550260

Reaction notes

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