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

HRID 985186Notes

Reaction equation

[CH2:1]([Li])CCC.[CH3:6][O:7][C:8]1[CH:9]=[CH:10][C:11]2[CH:15]=[CH:14][S:13][C:12]=2[CH:16]=1>C1COCC1.C([O-])(O)=O.[Na+]>[CH3:6][O:7][C:8]1[CH:9]=[CH:10][C:11]2[CH:15]=[C:14]([CH3:1])[S:13][C:12]=2[CH:16]=1

Participants

Conditions

Temperature: -10 °C

Procedure

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.

Workup

additionto addition of CH3l (4.2 ml, 9.58 g, 67 mmole)
temperatureto gradually warm to room temperature
customThe layers were separated
extractionthe aqueous phase was extracted with EtOAc (2×100 ml)
dry with materialThe combined organic extracts were dried over Na2SO4
concentrationconcentrated, in vacuo

Sources & evidence

ORD record: ord-33e5344054ab4fbcb8884deca40f9d58
Source dataset: uspto-grants-2005_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06869962B2

Reaction notes

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