Özet

Regio-and stereoselective synthesis are described for convenient preparation of hydroxy-and methoxynaphthalenes starting from naphthalene (\textbf {1}).\textit {cis, cis, trans}-2, 3, 5, 8-Tetrabromo-4-methoxy-1, 2, 3, 4-tetrahydronaphthalen-1-ol (\textbf {6}),\textit {cis, cis, trans}-2, 3, 5, 8-tetrabromo-1, 4-dimethoxy-1, 2, 3, 4-tetrahydronaphthalene (\textbf {7}), and\textit {cis, cis, cis}-2, 3, 5, 8-tetrabromo-1, 4-dimethoxy-1, 2, 3, 4-tetrahydronaphthalene (\textbf {8}) were obtained with silver-induced substitution of\textit {trans, cis, trans}-1, 2, 3, 4, 5, 8-hexabromo-1, 2, 3, 4-tetrahydronaphthalene (\textbf {3}). Base-promoted aromatization of dimethoxides\textbf {7} and\textbf {8} afforded 3, 5, 8-tribromo-1-methoxynaphthalene (\textbf {9}) and 2, 5, 8-tribromo-1-methoxynaphthalene (\textbf {10}). The reaction of\textbf {6} with sodium methoxide formed compounds\textbf {10} and 3, 5, 8-tribromonaphthalen-1-ol (\textbf {16}). Bromination of\textbf {9} and\textbf {16} with Br in dichloromethane at room temperature produced 2, 3, 5, 8-tetrabromo-1-methoxynaphthalene (\textbf {14}) and 2, 3, 4, 5, 8-pentabromonaphthalen-1-ol (\textbf {18}), respectively, while compound\textbf {10} did not react in the same conditions. Pyridine-induced elimination of hexabromide\textbf {3} afforded 1, 4, 6\textbf {-} tribromnaphthalene (\textbf {21}) in 99 {\%} yield and thermolysis of the hexabromide\textbf {3} gave mainly 1, 4, 6, 7-tetrabromonaphthalene (\textbf {22}). Tetrabromide\textbf {22} was transformed to 1, 4, 6, 7-tetramethoxynaphthalene (\textbf {23}) by copper-assisted nucleophilic substitution reaction.

Anahtar Kelimeler

Base-promoted elimination | Bromonaphthalene | Hydroxynaphthalene | Methoxynaphthalene | Silver-induced substitution

Atıf Sayıları
Google Scholar	1

Polybrominated methoxy- and hydroxynaphthalenes

Paylaş