2-Acetyl-5-bromo-6-methoxynaphthalene

When dissolved in tetrahydrofuran, PTT (like pyridinium hydrobromide perbromide) is a source of Brf ions, the properties of which are different from those of molecular bromine. In particular, it is much less electrophilic and less reactive toward aromatic rings and double bonds. It is thus a selective hrominating reagent for ketones or ketals - when the molecule has double bonds or activated aromatic nuclei which would be attacked by bromine. The two examples of use of this reagent clearly differentiate between its reactivity from that of bromine. Reaction of bromine with 2-acetyl-6-methoxynaph-thalene (in ether solution) gives a mixture, the main constituent of which is the product resulting only from ring bromina-tion (2-acetyl-5-bromo-6-methoxynaphthalene). ... 

---