Ciclizações intramoleculares atraves da decomposição acida de azidas aromaticas

AUTOR(ES)
DATA DE PUBLICAÇÃO

1986

RESUMO

Recently, the arylnitrenium ions have been receiving growing attentions because of their synthetic applications. Interest in this ion is also due to its possible intermediation as reactive metabolites of amino and nitroaromatic coumpounds, which present mutagenic and carcinogenic activities. We have found that six membered rings can be readily prepared by the formation of a intra molecular C-C bound and that five and six membered lactones may also be generated by the acid decompositions of m-substituted aryazides. The intramolecular nucleophilic attack of p-substitu- te arylnitrenium ions leading to the formations of a spiro bond is described. The decompositions of 4 -azido-2-hydroxy-5-methyl-benzophenone - and the 4 -azido-5-methyl-2-methoxybenzophenone in trifluoromethanesulfonic acid (TFMS) yielded reductions products 4 -amino-2-hydroxy-5-methylbenzophenone and 4 -amino-2-methoxy-5-methylbenzophenone as well as the reductions products formed by the counter-ions additions to the acid (4 -amino-2-hydroxy-5-methyl-3 - trifluorometanessulfonatebenzophenone and 4 -amino-2- methoxy-5-methyl-3 -trifluoromethanesulfonatebenzophenone). The basic nucleus of the spiro lactone geodoxin could be obtained by the acidic decompositions of either 4 -azidophenyl salicylate or 4 -azido-2-carboxydiphenyl ether. When the former was treated in acidic medium, the hydrolysis of the esther followed by the formations of the tetra (oxycarbonyl-l,2-phenylene) in minor quantity was observed. The second compound reacts with trifluoromethanesulfonic acid forming the cyclized product in 50% yield. The 11H-dibenzo b,e 1,4 -dioxepin-11-one can be obtained 11 by the decompositions of 3 -azidophenylsalicylate or 3 -azido-2-carboxydiphenyl ether. As observed for the 4 -azidophenylsalicylate, cyclizations of the 3 -azidophenyl salicylate did not occur. The 3 -azido-2-carboxydiphenyl ether was decomposed in trifluoracetic acid at 60°C. The ,cyclized product was isolated, in 30% yield. The azides used in the decompostions were synthetized by known reactions with good yields.Structure determinations were carried out by meam of IR, Hnmr, Cnmr and mass spectrometry.

ASSUNTO(S)

compostos aromaticos decomposição quimica

ACESSO AO ARTIGO

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