Hydrochloric Acid → 4,5-Dihydro-8-methylthio-2-phenylfuro[3,4-e]benzothiazole-6-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

Ethyl 4,5-dihydro-8-methylthio-2-phenylfuro[3,4-e]benzothiazole-6-carboxylate (1.32 g) was suspended in a mixed solvent of ethanol (10 ml) and tetrahydrofuran (15 ml); a 2 N aqueous solution of sodium hydroxide (5.3 ml) was added at 50° C. After the reaction mixture was stirred at 50° C. for 1.5 hours, the solution obtained was poured over water (300 ml), acidified with concentrated hydrochloric acid, and extracted with ethyl acetate-tetrahydrofuran (3:1, v/v). The organic layer was washed with water and dried (MgSO4), after which the solvent was distilled off to yield 4,5-dihydro-8-methylthio-2-phenylfuro[3,4-e]benzothiazole-6-carboxylic acid (1.14 g, 93.4%), which was then recrystallized from chloroform-methanol. Colorless prisms. Melting point 206-207° C. (decomposed).

Provenance & Evidence