p-Toluenesulphonyl cyanide → 7-Methoxy-1-benzothiophene-2-carbonitrile

Participants

Reaction Steps

To a solution of 1-benzothien-7-yl methyl ether (1 g, 6.1 mmol) in THF (12 mL) at −78° C. was added a solution of 2.5 M n-butyllithium in hexanes (2.9 mL, 7.3 mmol). After stirring for 1.5 hr this solution was added dropwise to a solution of tosyl cyanide (1.66 g, 9.1 mmol) in THF (8 mL), this was left stirring at −78° C. for 0.5 hr and then warmed to room temperature. After 16 h this was poured onto ice-water and extracted with dichloromethane (3×50 mL). The combined organic extracts were washed with water, dried MgSO4) and the solvent removed in vacuo to give an oil. This was purified by flash chromatography with a gradient of 0-30% ethyl acetate in hexane to give the title compound (0.31 g, 27%); δH (300 MHz, CDCl3) 7.79 (1H, s, 3-ArH), 7.46-7.38 (1H, m, 4-ArH), 7.37-7.31 (1H, m, 5-ArH), 6.88-6.82 (1H, m, 6-ArH) and 3.94 (3H, s, OCH3). Starting material 1-benzothien-7-yl methyl ether was recovered from the reaction (0.56 g, 56%); δH (300 MHz, CDCl3) 7.45-7.29 (4H, m, ArH), 6.75 (1H, m, ArH), 4.00 (3H, s, OCH3).

Provenance & Evidence