6-Methoxy-1-benzothiophene → 6-Methoxy-2-methylbenzo[b]thiophene

Participants

Reaction Conditions

Reaction Steps

A 2.5 M solution of n-butyllithium in hexanes (20 ml, 50 mmole) was added under argon to a solution of 6-methoxybenzo[b]thiophene 1a (3.68 g, 22.4 mmole) in THF (150 ml) at −75°. After stirring at −75° for a further 30 minutes, the cooling bath was exchanged and the reaction warmed to −10° C. prior to addition of CH3l (4.2 ml, 9.58 g, 67 mmole). The resultant mixture was stirred at 0° C. for an additional 30 minutes, then allowed to gradually warm to room temperature before diluting with saturated NaHCO3 (150 ml). The layers were separated and the aqueous phase was extracted with EtOAc (2×100 ml). The combined organic extracts were dried over Na2SO4 and concentrated, in vacuo, to give 4.2 g of an amber oil which was purified by silica gel chromatography. Elution with hexane: Et2O (98:2) and evaporation of the appropriate fractions gave 3.63 g (91%) of a colourless oil. 1H NMR (DMSO-d6) δ7.57 (1H, d, J=8.7 Hz), 7.43 (1H, d, J=2.4 Hz), 6.99 (1H, s), 6.92 (1H, dd, J=2.4, 8.7 Hz), 3.78 (3H, s), 2.50 (3H, s). Anal. Calcd. for C10H10OS: C, 67.38; H, 5.66; S, 17.99. Found: C, 67.42; H, 5.74; S, 17.87.

Provenance & Evidence