| abstract |
A tranexamic acid prodrug of general formula (II), is prepared by conversion of tranexamic acid in aqueous solution into a salt. An aromatic aldehyde of the formula Ar-CHO, lacking α-hydrogen atom is added to the solution and water is removed so as to form a salt of formula (a). The obtained suspension of anhydrous N-substituted tranexamic acid salt is esterified with 1-halogenethyl ethyl carbonate, wherein the halogen is chloro or bromo, and the halogenide formed and possibly present catalyst are removed. Protected esters of formula (b) wherein R signifies phenyl or naphthyl which may be substituted with lower alkyl or lower alkoxy groups or halogen atoms, are novel intermediates which can be used for the preparation of the prodrug (II). |