Maleic Anhydride → HCID 67867837, compound

Participants

Reaction Steps

A solution of 5-chloro-3-(4-hydroxypiperidinocarbonylmetyl)benzothiazolin-2-one (3.2 g) in dry pyridine (2.5 ml) and dry tetrahydrofuran (50 ml) was cooled, to which a solution of maleic anhydride (1.0 g) in dry tetrahydrofuran (5 ml) was gradually dropwise added under stirring. The mixture was refluxed for two hours and then left overnight. The solvent was evaporated off under vacuum from the reaction mixture, and the residue was dissolved in 5% aqueous sodium bicarbonate (20 ml). The solution was cooled and adjusted to pH 2 with 1% hydrochloric acid. The precipitated crystals were collected by filtration, washed with water and then subjected to chromatography on silica gel eluting with ethanol/benzene (1:1). The solvent was evaporated off under vacuum from the eluate at below 50° C. The residue was recrystallized from isopropyl alcohol to yield the title compound as colorless crystals (2.1 g). m.p. 197°-198° C.

Provenance & Evidence