Pyridine → 1-Naphthalenecarboxylic acid, 6-methoxy-5-(trifluoromethyl)-, methyl ester

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Reaction Conditions

Reaction Steps

A mixture of 5-iodo-6-methoxy-1-naphthalenecarboxylic acid methyl ester (10.26 g, 30 mmoles, described in Example 1f), trifluoromethyl iodide (12 g, 61.2 mmoles), freshly prepared copper powder (5.7 g, prepared according to the procedure of R. Q. Brewster and T. Groening, "Organic Synthesis", Coll. Vo. II, John Wiley and Sons, New York, N.Y., U.S.A., 1948, p. 445) and pyridine (45 ml) was charged into a stainless steel autoclave. The vessel was shaken and heated at 120° C. for 20 hr and cooled to room temperature. The mixture was diluted with diethyl ether-ethyl acetate (1:1). The insoluble material was removed by filtration. The filtrate was washed with 1N aqueous HCl, water and dried (MgSO4). The solvent was removed under reduced pressure. The residue was crystallized from ethanol to give 6.4 g of 5-(trifluoromethyl)-6-methoxy-1-naphthalenecarboxylic acid methyl ester; mp 79°-80° C.; NMR (CDCl3) δ 3.95 (s, 6 H), 8.00 (m, 5H). A mixture of the latter ester (6.3 g, 22 mmoles), 1N aqueous NaOH solution (34.12 ml) and methanol (100 ml) was stirred at 20°-22° C. for 4 hr. The mixture was adjusted to pH 7 with 1N aqueous HCl, methanol was removed from the mixture by distillation and the concentrated mixture was made acidic (pH 2) with 1N aqueous HCl. The resulting precipitate was collected and dried to yield 6 g of the title compound; mp 218°-219° C.; NMR (DMSO-d6) δ 4.0 (s, 3H), 8.3 (m, 5H), 10.6 (broad, 1H).

Provenance & Evidence