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

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Reaction Steps

(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.

Provenance & Evidence