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

Participants

Reaction Conditions

Reaction Steps

A total of 9.0 g of anhydrous aluminum chloride was suspended in 151.3 g of 1,2-dichloroethane by stirring in an atmosphere of nitrogen gas and was cooled to 0° C. To the cooled suspension was added dropwise a mixture of 7.98 g of methyl 2-chloroformyl-3-(3′-chlorophenyl)-propionate prepared in Example 1 and 151.3 g of 1,2-dichloroethane held at 5° C. or below, followed by stirring under the same conditions for 2 hours. The reaction mixture was added dropwise to 53.6 g of 1.7% by weight hydrochloric acid cooled at 5° C. or below, followed by stirring under the same conditions for 1 hour. The 1,2-dichloroethane layer was separated from the aqueous layer, and the product was further extracted from the aqueous layer with two portions of 15.1 g of 1,2-dichloroethane. The 1,2-dichloroethane layers were collected and were washed with 33.0 g of water, from which 1,2-dichloroethane was removed 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