(4-Methoxyphenyl)boronic acid → 7-(4-Methoxyphenyl)benzo[b]thiophene

Participants

Reaction Conditions

Reaction Steps

To a 50 ml round bottom flask was added Pd2(dba)3 (107 mg, 0.117 mmol), KF (2.25 g, 3.9 mmol), 4-methoxyphenylboronic acid (2.14 g, 14.1 mmol), and the flask was purged with nitrogen. Anhydrous THF (25 ml) was then added followed by 7-bromo-1-benzothiophene (2.5 g, 11.73 mmol) in 5 ml THF followed by the addition of P(Cy)3 (100 mg, 0.352 mmol). After 4 h at ambient temperature no product was observed. Heating to 60° C. overnight afforded approx. 50% completion. After the addition of another 2% Pd2(dba)3 (215 mg), 0.1 equivalent boronic acid (26 mg) and THF, the reaction was complete in 2 h. The reaction was cooled, diluted with ether, filtered through a silica plug and concentrated to 3.33 g amber oil. Purification by column chromatography (load: 5% EtOAc/hexanes to 10% EtOAc/hexanes) afforded 2.75 g (97.5%) product as a light yellow solid: mp 74–75° C.; 1H NMR (300 MHz, DMSO-d6): δ 3.84 (3H, s), 7.11 (2H, d, J=8.7 Hz), 7.37 (1H, d, J=7.1 Hz), 7.48 (1H, t, J=7.6 Hz), 7.54 (1H, d, J=5.5 Hz), 7.67 (2H, d, J=8.7 Hz), 7.79 (1H, d, J=5.5 Hz), 7.86 (1H, dd, J=7.4 Hz, 0.8 Hz); MS (ESI) m/z 239 ([M−H]).

Provenance & Evidence