Indomethacin → [1-(p-Chlorobenzoyl)-5-methoxy-2-methyl-3-indoleacetoxy]-benzyl acetate

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Reaction Steps

180 g (0.503 mol) of 1-(p-chlorobenzoyl)-5-methoxy-2-methyl-3-indoleacetic acid were dissolved in 900 ml of dimethylformamide, 35 g of triturated, anhydrous potassium carbonate were added and stirring was continued for 45 minutes at 50°C. 128 g (0.558 mol) of benzyl bromoacetate were then added and the mixture was stirred for 3 hours at 50°C. After evaporating the dimethylformamide under vacuum, the residue was dissolved in chloroform, washed several times with water, dried over sodium sulphate and then separated by chromatography on alumina. The eluate was concentrated by evaporation and the residue recrystallised from alcohol. The [1-(p-chlorobenzoyl)-5-methoxy-2-methyl-3-indoleacetoxy]-benzyl acetate which formed melted at 93°-94°C and the yield was 81% of the theoretical. This benzyl ester was converted as described in Example 1 or 2 into the free acid.

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