Tetrahydrofuran → 1-Bromo-4-(1-bromoethyl)benzene

Participants

Reaction Conditions

Reaction Steps

To a 50 mL round-bottomed flask containing polystyrene resin (5 Scheme 18, 200 mg, 0.30 mequiv/g) in dry THF (15 mL) at −78° C. was added methylmagnesium bromide (10 equiv). The reaction slurry was stirred for 1 h at −78° C., then warmed slowly to room temperature and further stirred for 2 h. After cooling the flask to −20° C., saturated NH4Cl (0.5 mL) was added, and the mixture was stirred for 20 min at room temperature. The resin was filtered and washed with 1:1 THF/water (twice), water (twice), methanol (twice), CH2Cl2 (twice), then dried under reduced pressure. To a slurry of resin in CH2Cl2 (8 mL) was added Br2 (100 μL). After agitation for 20 min, the cleavage solution was removed, and the resin was rinsed with CH2Cl2 (5 mL). Concentration of the combined filtrates gave 4-bromo-α-methyl benzyl bromide (7 Scheme 18) as a colorless oil (12 mg, 75%); 1H NMR (300 MHz, CDCl3) δ 2.03 (d, J=6.97 Hz, 3 H), 5.17 (q, J=6.97 Hz, 1 H), 7.32 (d, J=8.49, 2 H), 7.49 (d, J=8.49, 2 H); 13C NMR (75 MHz, CDCl3) 27.0, 48.5, 122.4, 128.8 (2C), 132.1 (2C), 142.5.

Provenance & Evidence