Tetrahydrofuran → 3,5,7-Trimethyl-2E,4E,6E,8E-undecatetraene

HRID 1085770Notes

Reaction equation

HRID 1085770 reaction equation
[Br-].[CH3:2][CH:3]([P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)/C=C/CC.O1[CH2:31][CH2:30][CH2:29][CH2:28]1.C([Li])CCC.[CH3:37]/[C:38](=[CH:41]\[C:42](\[CH3:45])=[CH:43]\[CH3:44])/[CH:39]=O>CCCCC.O>[CH3:28]/[C:29](/[CH:37]=[C:38](\[CH3:39])/[CH:41]=[C:42](\[CH3:45])/[CH:43]=[CH:44]/[CH2:2][CH3:3])=[CH:30]\[CH3:31]

Participants

7

Reactant 4

HCID 8028TetrahydrofuranHCID 113324592,4-Dimethyl-2E,4E-hexadienalHCID 20058850(1-Methyl-(E)-2-pentenyl)triphenylphosphonium bromideHCID 178418339Butyllithium

Product 1

HCID 146560473,5,7-Trimethyl-2E,4E,6E,8E-undecatetraene

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 8003PentaneSolvent

Procedure

(1-Methyl-(E)-2-pentenyl)triphenylphosphonium bromide (0.40 g, 0.0009 mole), from Example 11, was added to a flask with 2 ml dry tetrahydrofuran. The reaction was run under nitrogen, and the flask was equipped with a magnetic stirrer. The mixture was cooled over ice, and butyllithium (2.5 m in hexane) was added dropwise until the color change became permanent; then an additional 0.4 ml (0.001 mole) was added. After 5 min, 100 mg (0.0008 mole) of 2,4-dimethyl-(E,E)-2,4-hexadienal (4, R1 =H) was added. The mixture was warmed to room temperature, stirred for 2 hr, then cooled over ice again. Water (1 ml) and pentane (3 ml) were added. The aqueous layer was washed twice with 2 ml pentane. The combined organic layers were washed three times with water and dried over Na2SO4. After the product was passed through a silica column with hexane, both the (E,E,E,E) and (E,E,Z,E) isomers were present (47% and ca. 40%, respectively, by GC). The isomers were resolved by HPLC on the silver-nitrate column, as described in Example 10.

Workup

  1. customthe flask was equipped with a magnetic stirrer
  2. additionwas added dropwise until the color change
  3. additionthen an additional 0.4 ml (0.001 mole) was added
  4. temperaturecooled over ice again
  5. washThe aqueous layer was washed twice with 2 ml pentane
  6. washThe combined organic layers were washed three times with water
  7. dry with materialdried over Na2SO4

Sources & evidence

ORD record
ord-0586f934bc274d53b604e25b180fb90d
Source dataset
uspto-grants-1991_04
Patent number
US05011683

Reaction notes

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