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 3N 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