Pyridine → HCID 23050251, compound

Participants

Reaction Steps

A mixture of 5,6-dimethoxy-benzo[b]thiophene-2-carboxylic acid (68.8 g), dry toluene (350 ml), thionyl chloride (126 ml) and pyridine (1.75 ml) was stirred and heated at reflux for 4 hours. The resultant mixture was cooled, evaporated to dryness under vacuum and the residue was purged with dry toluene (3×250 ml). The resulting crude acid chloride was suspended in dioxan (160 ml) then cooled in an ice bath and treated in one portion with concentrated ammonium hydroxide solution (33% w/w, 900 ml). This gave a suspension of brown solid which was stirred for two hours then filtered, washed with water and dried under vacuum over calcium chloride at 60° C. to give 5,6-dimethoxy-benzo[b]thiophene-2-carboxamide (62.5 g), m.p. 211°-213° C.

Provenance & Evidence