Friedel–Crafts reactions. Part XXIV. Diacylations of 2,7-dimethylnaphthalene. Deuterium-labelling as an aid to structural determinations
Friedel–Crafts diacetylation of 2,7-dimethylnaphthalene gives mixtures of 1,3- and 1,5-diacetyl-derivatives, the latter usually predominating. A corresponding benzoylation afforded a mixture of 1,5- and 1,8-dibenzoyl-derivatives, with the latter predominating. The structures of the dibenzoyl derivatives followed from the 1H n.m.r. spectra of ketones deuterium-labelled in the phenyl rings. Stereochemical aspects of the diacylation reactions and products are discussed.