Bromide ion → 4-Bromobiphenyl

Participants

Reaction Conditions

Reaction Steps

A solution of 4-bromobiphenyl (7.42 g, 31.87 mmol) in 40 mL THF was prepared, and 10 mL was added to Mg (0.85 g, 35.05 mmol) and one crystal of 12 in THF (10 mL). The Grignard reaction was initiated with the aid of gentle warming by a heat gun. After the iodine color had dissipated, the remaining 30 mL of bromide solution was added dropwise to the reaction mixture. After the reflux subsided, the solution was warmed over an oil bath (70° C.) for 30 minutes, then cooled to 0° C. N-benzyl-(S)-proline methyl ester (5, 2.18 g, 9.96 mmol) in THF (10 mL) was added. After the addition, the solution was allowed to warm to room temperature and stirred for another 8 hours. Saturated NH4Cl (150 mL) was added and the resulting mixture was diluted with Et2O (200 mL). The phases were separated and the organic phase was washed with H2O and brine, dried (MgSO4), and concentrated. The residue was purified over a short silica gel column using 5 to 20% EtOAc/pet ether to a give a white solid, which was recrystalized with CH2Cl2/pet ether to obtain white needles (4.106 g, 83%): mp 85-86° C., 1H NMR (300 MHz, CDCl3) δ 1.60-1.74 (m, 2 H), 1.76-1.88 (m, 1 H), 1.94-2.08 (m, 1 H), 2.40 (dd, J=16.6, 9.0 Hz, 1 H), 2.92-3.00 (m, 1 H), 3.10 (d, J=12.7 Hz, 1 H), 3.38 (d, J=12.5 Hz, 1 H), 4.06 (dd, J=9.3, 4.6 Hz, 1 H), 5.04 (s, 1 H), 7.04-7.60 (m, 14H), 7,68 (d, J=8.3 Hz, 2 H), 7.82 (d, J=8.3 Hz, 2 H).

Provenance & Evidence