Hydrochloric Acid → HCID 53729196, compound

Participants

Reaction Steps

A solution of 9-butyl-1,4-dihydro-4-oxo-5H-[1]benzothiopyrano-[4,3-b]pyridine-2-carboxylic acid (1.82 g, described in Example 84) in 350 ml of anhydrous methanol saturated with hydrogen chloride is heated at reflux for 17 hours. The solvent is removed by evaporation. Water is added to the residue and the aqueous mixture is extracted with chloroform. The organic extract is dried over magnesium sulfate and evaporated. The residue is subjected to chromatography on silica gel using benzene-ethyl acetate (4:1) as eluant. The eluate is evaporated and the residue is crystallized from ether to give the title compound, m.p. 144°-146° C.

Provenance & Evidence