Aryloxy groups, electronic effects

Disubstituted-6-bromo-2,3-diazepinium salts react with nucleophiles with displacement of the bromine atom and this reaction has been used to prepare 6-aryloxy, 6-alkoxy, and 6-amino derivatives <93AHC(56)i>. An explanation proposed for the nucleophilic attack at the electron-rich 6-position of the diazepinium salt is the involvement of small amounts of the bis-imine tautomer, undetectable by NMR, which would be electrophilic at C-6 because of the combined effects of the bromo atom and the two adjacent azomethine groups. In many cases, the 6-bromo-... 

In an analogous reaction, 2-benzylpyridine was prepared from reaction of pyridine N-oxide and benzyltrimethylsilane in the presence of tetrabutylammonium fluoride. 9 Substituent effects on the base-catalysed rearrangement of N-(aryloxy)pyridinium salts have been studied. A 3-methyl group directs rearrangement to the 6-position whereas an electron-withdrawing group directs rearrangement mainly to the 2-position. With a suitable choice of substituent it is therefore possible to form tricyclic products as illustrated in Scheme 11. 

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