Iodine → 3(2-Propynyl)benzaldehyde ethylene acetal

Beteiligte Stoffe

Reaktionsschritte

Dry Mg (0.74 g) under dry N2 in a flask is covered with THF (10 ml) and a crystal I2 added. 5 ml of a solution of 3-bromobenzaldehyde ethylene acetal (7.0 g) in THF (30 ml) is added and kept until it becomes warm, when it is cooled to 15°, and the remainder of the acetal solution added over 15 minutes, then stirred for an additional 1 hour. A mixture of methoxyallene (2.45 g), copper (1)chloride (0.30 g) and THF (30 ml) is cooled to -20°. The above Grignard solution (under moisture excluding conditions) is then added to this solution during 5 minutes, and allowed to warm to 20° with stirring over 30 minutes. Saturated aqueous ammonium chloride is added and the product is extracted with ether. The ether layer is washed with water, dried (MgSO4) and the residue distilled in vacuo. Yield 4.3 g (75%) 89°-96° (0.03 m Hg), nD20 1.5422.

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