Boron tribromide → 6-Hydroxy-n,2-dimethyl-1-benzothiophene-3-carboxamide

Participants

Reaction Steps

A 1.0 M solution of BBr3 in CH2Cl2 (6 ml, 6 mmole) was added to a solution of 6-methoxy-2-methylbenzo[b]thiophene-3-carboxylic acid methylamide 1c (683 mg, 2.9 mmole) in CH2Cl2 (60 ml) at 0°. The reaction was left stirring for 14 hours, gradually warming to ambient temperature, then poured onto crushed ice (˜70 g). The layers were separated and the aqueous phase was extracted with EtOAc (2×50 ml). The combined organic extracts were dried over Na2SO4 and concentrated, in vacuo, to give 623 mg (97%) of a beige solid which was employed without further purification. 1H NMR (DMSO-d6) δ9.56 (1H, s), 8.11 (1H, q, J=4.4 Hz), 7.53 (1H, d, J=8.7 Hz), 7.18 (1H, d, J=2.3 Hz), 6.83 (1H, dd, J=2.3, 8.7 Hz), 2.79 (3H, d, J=4.4 Hz), 2.50 (3H, s).

Provenance & Evidence