Heterosubstituted or functionalized derivatives of 1-and 2-(trifluoromethyl)naphthalenes emanating from aryne adducts

More than two dozen new CF3-substituted naphthalene derivatives were prepared in an expedient way by employing 3- and 4-(trifluoromethyl)benzyne as the key intermediates. 2- and 4-Chlorobenzotrifluoride were treated with butyllithium and the organometallic species thus generated were allowed to decompose in the presence of furan. The resulting cycloadducts 1 and 14 were reduced to the (trifluoromethyl)naphthalenes 2 and 15, ring-opened to the (tritluoromethyl)naphthols 3, 16 and 17 and transformed to the dibromo adducts 5 and 18. The latter were stereoselectively converted into the bromo-1,4-epoxy-1,4-dihydro(trifluoromethyl)naphthalenes 6, 7, 19 and 20 and, by deoxygenation, into various bromo(trifluoromethyl)naphthalenes 8, 9, 21 and 22. Trifluoromethyl substituted naphthoic acids 10-13 and 23-26 were obtained when the bromo compounds 6-9 and 19-22 were subjected to a halogen/metal permutation followed by carboxylation.