合成路线1

Curtius rearrangement of indanylacetic acid (I) using diphenylphosphoryl azide (DPPA) in the presence of benzyl alcohol afforded benzyl carbamate (II). Hydrogenolytic deprotection of (II) in the presence of palladium catalyst then provided amine (III), which was condensed with 4-chlorobenzenesulfonyl chloride (IV) to give sulfonamide (V). Subsequent Friedel Crafts reaction of (V) with ethyl a-chloro-a-(methylsulfanyl)acetate (VI) and SnCl4 furnished sulfide (VII), from which the methylthio group was removed by reductive treatment with Zn dust in AcOH yielding (VIII). Finally, alkaline hydrolysis of the indanylacetic ester (VIII) provided the title carboxylic acid, isolated as the corresponding sodium salt.