1-(5-Bromothiophen-3-yl)ethan-1-one → HCID 68509357, compound

Participants

Reaction Steps

To a solution of ethyl-triphenyl-phosphonium bromide (27.0 mmol, 10.02 g) in anhydrous THF (90 mL) was added at 0° C. a solution of KOtBu (27.0 mmol, 27 mL, 1 M in THF). The solution was stirred for 1 h at room temperature, cooled down to −78° C. and treated with a solution of 1-(5-bromo-thiophen-3-yl)-ethanone (19.1 mmol, 3.92 g) in anhydrous THF (30 mL) at the temperature. The reaction mixture was slowly warmed to room temperature overnight with stirring. After dilution of the reaction mixture with EtOAc (200 mL), it was washed with water (70 mL×2) and brine (70 mL), dried (MgSO4) and concentrated in vacuo. Chromatography on SiO2 (Hexanes/EtOAc, 20/1) gave 4.15 g (100%) of 2-bromo-4-(1-methyl-propenyl)-thiophene as a liquid of isomeric mixture (Z/E isomer, 9/1). Z isomer; 1H NMR (400 MHz, CDCl3) δ 7.04 (d, J=1.7 Hz, 1H), 6.98 (d, J=1.7 Hz, 1H), 5.55 (m, 1H), 1.97 (quint, J=1.5 Hz, 3H), 1.72 (dq, J=7.0, 1.5 Hz, 3H). E isomer; 1H NMR (400 MHz, CDCl3) δ 7.17 (d, J=1.7 Hz, 1H), 6.94 (d, J=1.7 Hz, 1H), 5.90 (m, 1H), 1.94 (quint, J=1.1 Hz, 3H), 1.77 (d, J=6.9, 1.0 Hz, 3H).

Provenance & Evidence