Sodium Hydroxide → 5,8-Dimethoxy-3,4-dihydronaphthalene-2-carboxylic acid

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Reaction Steps

Ethyl 3,4-dihydro-5,8-dimethoxy-2-naphthoate (7.50 g, 28.6 mmole) is added to a mixture of ethanol (50 ml) and a 2 N aqueous solution of sodium hydroxide (25 ml), and the resultant mixture is boiled for 5 hours. After completion of the reaction, the reaction mixture is concentrated to the one-fourth of the amount, diluted with water (50 ml) and washed with ether (100 ml×2). The aqueous layer is made acidic with conc. hydrochloric acid, and the precipitated white solid is collected by filtration and then dried (6.50 g, 97%). M.P.<220° C. Recrystallization from ethanol affords an analytical sample of 9b as colorless needles. M.P.<220° C. IRνmaxNujol cm-1 : 1660 (COOH), NMR (in CDCl3 - DMSO-d6): 2.20-3.00 (4H, m, CH2CH2C=), 3.80 (3H, s, OCH3), 3.82 (3H, s, OCH3), 6.75 (1H, d, J=10.7Hz, one of aromatic protons), 6.93 (1H, d, J=10.7Hz, one of aromatic protons), 7.82 (1H, broad s, CH=).

Provenance & Evidence