Thallium trinitrate-mediated ring contraction of 1,2-dihydronaphthalenes: the effect of electron-donating and electron-withdrawing groups

• Autor(a) principal: Silva Jr.,Luiz F.
• Data de Publicação: 2005
• Outros Autores: Sousa,Raquel M. F., Ferraz,Helena M. C., Aguilar,Andrea M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532005000700012
• topic: ring contraction; oxidation; indans; thallium(III)

The oxidation of a series of 1,2-dihydronaphthalenes substituted in the aromatic ring was investigated with thallium trinitrate (TTN) in methanol or in trimethylorthoformate (TMOF) as solvent. In all cases, indans are produced, although the yield varied from excellent to poor, depending on the structure of the substrate. The presence of an electron-donating group in the substrate favors the rearrangement, whereas significant amounts of glycolic derivatives, as well as naphthalenes, were obtained in the oxidation of 1,2-dihydronaphthalenes bearing electron-withdrawing groups, such as Br and NO2. Mechanisms for the formation of each of these products are proposed.