Iodine → 2-[(4-Fluorophenyl)methyl]thiophene

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Reaction Steps

To a suspension of Mg (3 g, 0.123 mol) in THF (40 ml) was added a small amount of solid I2 (20 mg). The mixture was heated to reflux under nitrogen. To the mixture was then added the 2-bromothiophene solution (5 ml) (19.6 g of 2-bromothiophene in 40 ml of THF). After the iodine color disappeared, to the suspension was added the rest of 2-bromothiophene solution dropwise keeping reflux. After the addition, the mixture was heated under reflux for 2 h., then was cooled to room temperature. To this mixture was added 4-fluorobenzyl iodide (or 4-fluorobenzyl bromide) followed by Li2CuCl4 (5 ml) solution keeping the temperature under 40° C. using a cool water bath. The mixture was stirred at room temperature for 2 h. To the mixture was added sat. NH4Cl solution (100 ml), the mixture was stirred for 30 min., the organic layer was separated and washed with 10% sodium thiosulfate solution (50 ml), followed by distilled water (100 ml). The organic layer was then dried over MgSO4 and concentrated to give 19 g of 2-(4-fluorobenzyl)thiophene as an oil. Purification was achieved by vacuum distillation (110° C., 5 mm Hg).

Provenance & Evidence