Nitro-substituted naphthalenes studies

To derive the maximum amount of information about intranuclear and intemuclear activation for nucleophilic substitution of bicyclo-aromatics, the kinetic studies on quinolines and isoquinolines are related herein to those on halo-1- and -2-nitro-naphthalenes, and data on polyazanaphthalenes are compared with those on poly-nitronaphthalenes. The reactivity rules thereby deduced are based on such limited data, however, that they should be regarded as tentative and subject to confirmation or modification on the basis of further experimental study. In many cases, only a single reaction has been investigated. From the data in Tables IX to XVI, one can derive certain conclusions about the effects of the nucleophile, leaving group, other substituents, solvent, and comparison temperature, all of which are summarized at the end of this section. 

Some other aromatics azidated in this way included 1,2,3-trimethoxybenzene (at C-5), naphthalene (at C-l), mesitylene, etc. Mechanistic studies have shown that azide reacts as a nucleophile with aryl cation radicals formed through electron abstraction by BTI. With p-alkylanisoles bearing at least one benzylic proton, BTI and Me3SiN3 in acetonitrile gave sp3-C-substitution products, homolytically. Among the R groups were not only alkyls but also cyano, nitro and others [102]. 

There have been extensive studies on the triplet-state absorptions in nitro-naphthalenes 288 and methoxy-naphthalenes,289 from which it was concluded that the / -substituted compounds have T-T absorption spectra resembling closely those of the parent naphthalene, whereas -substitution leads to dramatically different spectra which can be associated with enhancement of the 3Ble+ <- 3BZu+ and 3 - B2u+ transitions of the parent. 

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