Bromide ion → (6Z,9Z)-18-bromooctadeca-6,9-diene

Participants

Reaction Conditions

Reaction Steps

A 1 liter RBF was charged with magnesium turnings (11.1 g, 463 mmol), anhydrous THF (65 mL) and stir-bar and flushed with nitrogen. In a separate flask, a solution of linoleyl bromide (140 g, 425 mL) in anhydrous THF (150 mL) was prepared, and 20 mL of this solution added to the magnesium. When most of the heat had dissipated, the remainder of the bromide was added over a period of 15 minutes. Temperature was then maintained at 45° C. for 4 h. The reaction was then cooled (0° C.). Using a dropping funnel, a solution of ethyl formate (32.4 g, 438 mmol) in anhydrous THF (150 mL) was added over a 40 minute period. The reaction was stirred overnight at room temperature. The reaction was cooled to −15° C. and 5N HCl (185 mL) added slowly. The mixture was transferred to a 2 L separating funnel separated. Water (150 mL) and hexane (150 mL) were added, the mixture washed, and again the aqueous removed. The organic was washed a final time with water (150 mL) and then concentrated to a yellow oil. The yellow oil was stirred with a mixture of EtOH (210 mL), water (30 mL) and KOH (15.8 g) for 1.5 h at room temp. The EtOH was evaporated and the residue treated with hexane (50 mL). 5N HCl (200 mL) was added via dropping funnel. The organic was washed with water (2×50 mL) evaporated, dried and purified by chromatography (0-5% EtOAc in hexane, 91 g, 81%).

Provenance & Evidence