RING TRANSFORMATIONS OF HETEROCYCLIC-COMPOUNDS .13. BIS(2,4,6-TRIARYLPHENYL) SUBSTITUTED BISPYRIDINIUM SALTS FROM METHYL-DERIVATIVES BY DOUBLE PYRYLIUM AND THIOPYRYLIUM RING TRANSFORMATIONS

The synthesis of hitherto unknown 4,4'-bis(2,4,6-triarylphenyl) substi tuted bispyridinium diperchlorates 3, in which the N-atoms are linked by a carbon chain, a heteroatom containing a carbon chain or a bis(met hylene) substituted aromatic/heteroaromatic ring, from 4,4'-dimethylbi spyridinium derivatives 2 by a double 2,6-[C-5+C] ring transformation of 2,4,6-triarylpyrylium and 2,4,6-triarylthiopyrylium salts 1/4 is re ported. Spectroscopic data of the bispyridinium diperchlorates 3 and t heir mode of formation are discussed.