Acetic Acid → 6-Methoxy-1,2,3,4-tetrahydronaphthalene-1-carboxylic acid

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Reaction Steps

As described with reference to Reaction Scheme I, compounds of Formula 2 can be converted to the intermediates of Formula 3 according to the procedure described by Belletire, et al. [Synthetic Commun., 12(10), 763-770 (1982)]. For example, to a 250 ml single neck round bottom reaction flask equipped with a magnetic stirrer, reflux condenser and nitrogen inlet, is added 6.0 g (21.79 mmol) of 1-cyano-1-trimethylsiloxy-6-methoxy-1,2,3,4-tetrahydronaphthalene. In one portion, 20.0 g (88.6 mmol) stannous chloride decahydrate followed by 20 ml glacial acetic acid and 20 ml concentrated hydrochloric acid is added. The reaction apparatus is immediately flushed with nitrogen and plunged into a preheated (140° C.) oil bath. With vigorous stirring the reaction mixture is heated at reflux for 65 hours, cooled to room temperature, diluted with 250 ml chloroform, the layers separated, and the aqueous layer again extracted with chloroform. The combined organic layers are extracted three times with 2N aqueous KOH, and the combined basic aqueous layers back-extracted with ether. The basic aqueous layer is acidified with ice-bath cooling, extracted three times with chloroform, the organic layers dried over magnesium sulfate, filtered, and the volatiles removed to give 6-methoxy-1,2,3,4-tetrahydronaphthalene-1-carboxylic acid, an intermediate of Formula 3, as a crystalline solid.

Provenance & Evidence