Hydrochloric Acid → 7-phenyl-3,4-dihydronaphthalene-2-carboxylic Acid

Participants

Reaction Conditions

Reaction Steps

A mixture of sodium methoxide (18.3 g), dimethyl carbonate (107 ml) and 7-phenyl-1-tetralone (15.1 g) was refluxed for 30 minutes. The reaction mixture was cooled to 0° C. To the mixture was gradually added 3N hydrochloric acid (200 ml), and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated sodium chloride solution, dried with anhydrous sodium sulfate and concentrated under reduced pressure to give a brown solid. The solid was dissolved in dichloromethane (100 ml), and to the mixture was added sodium boron hydride (1.60 g) at 0° C. To the mixture was added dropwise methanol (10 ml) for 30 minutes, and the reaction mixture was stirred for 4 hours at 0° C. To the mixture was added water (500 ml), and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated sodium chloride solution, dried with anhydrous sodium sulfate and concentrated under reduced pressure. The ressidue was dissolved in methanol (45 ml). To the mixture was added 2N sodium hydroxide (50 ml), and the mixture was refluxed for 2 hours. The reaction mixture was cooled to room temperature, acidified with concentrated hydro-chloric acid and extracted with ethyl acetate. The organic layer was washed with saturated sodium chloride solution, dried with anhydrous sodium sulfate and concentrated under reduced pressure. The residue was dissolved in Diglyme (1,1′-oxybis[2-methoxyethane]) (50 ml), and to the mixture was added concentrated hydrochloric acid (10 ml). The mixture was stirred for 2 hours at 100° C., and to the mixture was added water (500 ml). The mixture was extracted with ethyl acetate, and the organic layer was washed with saturated sodium chloride solution and concentrated under reduced pressure. The residue was dissolved in 1N sodium hydroxide (200 ml), washed with diethylether, acidified by adding concentrated hydrochloric acid to the aqueous layer and extracted with ethyl acetate. The organic layer was washed with saturated sodium chloride solution, dried with anhydrous sodium sulfate and concentrated under reduced pressure. The residue was recrystallized from ethanol-water to give 7-phenyl-3,4-dihydronaphthalene-2-carboxylic acid (7.47 g) as brown crystals.

Provenance & Evidence