Sodium Hydroxide → HCID 12561502, compound

Participants

Reaction Steps

A mixture of 3-methyl-4-oxo-4H,5H-[1]benzothiopyrano[4,3-b]pyran-2-carboxylic acid methyl ester (1.60 g, 5.56 mmoles, described in Example 7) in a solution of sodium hydroxide (0.5 g) in methanol (50 ml is refluxed for 2 hr and evaporated. The residue is dissolved in water, and the solution is washed with diethyl ether and added with stirring to 3 N hydrochloric acid (25 ml). The fine precipitate is collected, washed with very dilute hydrochloric acid, small amount of water and then dried (1.506 g), mp 299°-301° C. The precipitate is crystallized from dimethyl sulfoxide-water to obtain crystals of the title compound, mp 302°-303° C.

Provenance & Evidence