1.2.3.4- Tetrahydro- -toluic acid

The following examples may be cited to illustrate these generalizations. />-Toluic acid under conditions of the Birch reduction essentially as given in this procedure yields mainly 1,2,3,4-tetrahydro-/>-toluic acid (cis and trans) plus minor amounts of... 

Sodium in liquid ammonia and ethanol reduced benzoic acid to 1,4-dihy-drobenzoic acid. Reduction of p-toluic acid was more complicated and afforded a mixture of cis- and rranj-l,2,3,4-tetrahydro-p-toluic acid and cis-and tra j-l,4-dihydrotoluic acid. m-Methoxybenzoic acid yielded 1,2,3,4-tetrahydro-5-methoxybenzoic acid, and 3,4,5-trimethoxybenzoic acid gave l,4-dihydro-3,5-dimethoxybenzoic acid in 87% yield (after hydrogenolysis of the methoxy group para to carboxyl) [984. In the case of 4 -methoxy-biphenyl-4-carboxylic acid, sodium in isoamyl alcohol at 130° reduced completely only the ring with the carboxylic group, thus giving 92% yield of 4-(p-methoxyphenyl)cyclohexanecarboxylic acid [955]. 

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