1,8-Diazabicyclo(5.4.0)undec-7-ene → 4-Fluoro-7-methoxy-1-benzothiophene

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Reaction Steps

4-Fluoro-7-methoxy-1-benzothiophene-2-carboxylic acid (2.00 g, 8.84 mmol) was added in one portion to DBU (8 mL) and dimethyl acetamide (10 mL). This was heated in the microwave with 300W at 200° C. for 1 h. The reaction mixture was allowed to cool and poured onto water (100 mL). Product was extracted with hexane (2×100 mL), washed with aqueous hydrochloric acid (2 N, 50 mL), aqueous sodium hydroxide (2 N, 50 mL), and the combined organic extracts were dried (MgSO4) and concentrated in vacuo. The residue was purified by flash chromatography eluting silica gel with hexane:ethyl acetate [96:4] to give an oil (1.12 g, 70%); δH (300 MHz, CDCl3) 7.4 (2H, s, Ar), 6.9 (1H, t, Ar), 6.60 (1H, dd, Ar), 3.91 (3H, s, OCH3).

Provenance & Evidence