- Substituted naphthoic acid process
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6-Alkoxy-5-trifluoromethyl-1-naphthoic acids are prepared by (1) cyanating a 6-alkoxytetralone so as to form a 6-alkoxy-1-cyano-3,4-dihydronaphthalene, (2) converting the 6-alkoxy-1-cyano-3,4-dihydronaphthalene to a naphthoic acid precursor selected from a 6-alkoxy-1-cyanonaphthalene and a hydrocarbyl 6-alkoxy-1-naphthoate, (3) halogenating the naphthoic acid precursor to the corresponding 5-halo derivative, (4) trifluoromethylating the 5-halo derivative to replace the 5-halo substituent with a 5-trifluoromethyl group, and (5) hydrolyzing the resultant product to a 6-alkoxy-5-trifluoromethyl-1-naphthoic acid. In a preferred embodiment of the invention, the process is conducted so as to prepare 6-methoxy-5-trifluoromethyl-1-naphthoic acid, which, like the other products, is known to be useful as a pharmaceutical intermediate.
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