The use of N-bridgehead heterocyclic indolizinium ylide in the synthesis of aza-cyanine dyes

The reaction of 3-methyl-8-oxime-1-phenylpyrazolo [4,5-d]indolizinium (bezoindolizinium) ylide iodide with 2(4)-methyl substituted heterocyclic quaternary salts give 8[2(4)]-aza-monomethine cyanine dyes. Meanwhile, the reaction with carbonyl compounds followed by reaction with 2-methyl quinolinium methiodide salts afforded 5(2)-aza-trimethine cyanine dyes. On the other hand, the reaction of 5-formyl-2-methyl-4-phenylpyrazolo[4,5-d]indolizinium (benzoindolizinium) ylide iodide with hydroxylamine hydrochloride followed by reaction with N-methyl heterocyclic quaternary salts afforded the corresponding 5[4(1)]-aza-dimethine cyanine dyes. These new compounds are characterized with elemental analyses, visible absorption, IR, 13C NMR, 1H NMR and mass spectroscopy. The correlations between the structure and spectral properties of these dyes have been studied.