3-Cyanopyridine → HCID 23320889, compound

Participants

Reaction Steps

A solution of n-butyl-lithium in hexane (16.3 ml of 1.55M solution) was added to a stirred solution of 2,6-dibromo-3-methylbenzo[b]thiophene (7.65 g) in dry ether (150 ml) at -70° under dry nitrogen. The mixture was stirred for 30 minutes at -70° and then 3-cyanopyridine (2.60 g) in dry ether (50 ml) was added dropwise over 5 minutes. The resulting mixture was stirred at -70° for 3 hours and then at room temperature for a further 2 hours. Concentrated hydrochloric acid (40 ml) was added dropwise with stirring and the layers were separated. The ether layer was extracted with concentrated hydrochloric acid (20 ml) and the acid extracts were combined and warmed to complete hydrolysis of the intermediate ketimine salt. The solution was cooled and made alkaline with sodium hydroxide solution. The mixture was extracted several times with ethyl acetate and the combined extracts were washed with water and dried (Na2SO4). Evaporation of the solvent gave a solid which was chromatographed on silica gel. Elution with chloroform/petrol (b.p. 40°-60°) (2:1) gave a solid which was crystallised from ethyl acetate/petrol (b.p. 40°-60°) to give 6-bromo-3-methylbenzo[b]thien-2-yl pyrid-3-yl ketone (4.70 g), m.p. 110°-111°.

Provenance & Evidence