Ammonia → HCID 13604324, compound

Participants

Reaction Steps

6.83 g (33.4 mmoles) of 3-methoxy-5-methylthio-2-thiophene carboxylic acid (formula (II): R=CH3, R2 =SCH3) are refluxed together with 3.65 g (33.4 mmoles) of 2,3-diaminopyridine (formula III): R1 =H) in 80 ml of phosphorous oxychloride for 3 hours. The reaction mixture obtained is then introduced in portions into about 1.5 l of cold water, stirred well, filtered over Hyflo, made alkaline with potassium carbonate and some ammonia, and extracted several times with methylene chloride. The combined organic phases are dried over sodium sulfate and evaporated. The dark residue is suspended in about 300 ml of methanol, an excess of methanolic hydrochloric acid is added, heated to boiling, activated charcoal is added, filtered, and the solution is concentrated to about 100 ml and allowed to cool. A yellow hydrochloride precipitate of (I) is removed by suction and washed with a small amount of methanol. For preparing the free base, these crystals are suspended in 28 ml of methanol, 1.2 g of a 25% aqueous solution of ammonia are added, 80 ml of water are added, and the yellow crystalline precipitate is removed by suction, washed with water and dried. Yield: 4.24 g (46%), m.p. (ethanol) 224° C. (dec.).

Provenance & Evidence