Potassium Carbonate → (2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)trifluoromethanesulfonate

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Reaction Steps

The starting material, 2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-5-hydroxy-1H-inden-1-one, dissolved in dimethylformamide was treated with potassium carbonate and trifluoromethanesulfonyl chloride to form (2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)trifluoromethanesulfonate (Step 1). This material was subjected to triflate displacement by reaction with diethyl malonate to form diethyl-5-(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)malonate (Step 2). The malonate of Step 2 was then alkylated with ethyl 4-bromobutyrate to form diethyl 2-(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)-2-(ethoxycarbonyl)-1,6-hexanedioate (Step 3). Upon hydrolysis the hexanedioic acid is formed (Step 4) which undergoes monodecarboxylation by treatment with copper in quinoline to form a compound of the present invention such as 5-(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)pentanoic acid (Step 5). The starting materials used in these examples is obtained as shown in the Journal of Medicinal Chemistry, 20, 1400 (1977); and 21, 437 (1978). This synthetic route is illustrated below: ##STR3##

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