Hydrochloric Acid → 1H-Indene-2-carboxylic acid, 5-chloro-2,3-dihydro-1-oxo-, methyl ester

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Reaction Conditions

Reaction Steps

Under nitrogen atmosphere, 9.0 g of anhydrous aluminum chloride and 151.3 g of 1, 2-dichloroethane were stirred to yield a suspension, and the suspension was cooled to 0° C. A mixture of 7.98 g of methyl 2-chloroformyl-3-(3-chlorophenyl)-propionate prepared in Referential Example 1 and 151.3 g of 1,2-dichloroethane was added dropwise to the suspension while maintaining the temperature at 5° C. or below, followed by stirring under the same condition for 2 hours. The reaction mixture was added dropwise to 53.6 g of 1.7 percent by weight hydrochloric acid cooled to 5° C. or below, followed by stirring under the same condition for 1 hour. After separating the mixture into a 1,2-dichloroethane layer and an aqueous layer, the product in the aqueous layer was extracted with 15.1 g of 1,2-dichloroethane. This procedure was repeated a total of two times. The resulting 1,2-dichloroethane layers obtained by these procedures were collected and were washed with 33.0 g of water, followed by removal of 1,2-dichloroethane under reduced pressure. The concentrated residue was purified by silica gel column chromatography [mobile phase: hexane/ethyl acetate=4/1 (by volume)] to yield 5.21 g of methyl 5-chloro-1-oxo-2,3-dihydroindene-2-carboxylate as a beige solid in a yield of 70% on the basis of 3-(3-chlorophenyl)-2-methoxycarbonylpropionic acid.

Provenance & Evidence