Iodine → 4(Z-3-chloroallyl)benzaldehyde

Beteiligte Stoffe

Reaktionsschritte

Dry Mg (1.15 g) under dry N2 in a flask is covered with THF (10 ml) and a crystal of I2 added. 5 ml of a solution of 4-bromobenzaldehyde ethylene acetal (10.0 g) in THF (40 ml) is added and kept until it becomes warm, when it is cooled to 15°, and the remainder of the acetal added over 15 minutes, then stirred for an additional 1 hour. A mixture of ground lithium chloride (0.35 g) and copper (I) chloride (0.70 g) dissolved in THF is prepared, treated with Z-1,3-dichloropropene (8.0 g) produced by spinning band distillation of commercially available 1,3-dichloropropene comprising a mixture of the E and Z isomers and 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 for 16 hours. Saturated aqueous ammonium chloride is added and the organic layer evaporated under reduced pressure to a small residue, which is dissolved in THF (100 ml), cooled to -10°, treated with 3N HCl (50 ml), then stirred at 20° for 1 hour. The product is partitioned between ether and water, and the ether layer washed with saturated aqueous NaHCO3, H2O, saturated aqueous NaCl, dried (MgSO4) and the residue chromatographed on florisil. The fraction eluted by 15 % diethyl ether in petroleum ether bp 60°-80° C. is collected and purified by preparative HPLC. Yield 1.12 g (14%) nD20 1.5655.

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