92887-96-2Relevant academic research and scientific papers
Cyanine Dyes from 3a,4-Dihydro-3-methyl-4-phenyl-1H-pyrazolopyrimidin-6(5H)-one
Koraiem, Ahmed I. M.,El-Sogiar, Fawi M.
, p. 825 - 827 (2007/10/02)
The reaction of 3a,4-dihydro-3-methyl-4-phenyl-1H-pyrazolopyrimidin-6(5H)-one (I) with an equimolar amount of 2/4-methyl quaternary salts in the presence of sodium hydroxide as catalyst affords the asymmetrical pyrazolopyrimidine-6(2'/4'-)monomethine cyanines (IIa-c).Pyrimidone I also reacts with non-quaternised heterocyclic compounds for a longer period to give the corresponding asymmetrical monomethine bases (IIIa, b).The selective SeO2 oxidation of III yields 3-formyl derivatives (IV) which undergo condensation with 2-methyl quaternary salts to give the styrylcyanines (V).SeO2 oxidation of I followed by reaction of the resultant 3a,4-dihydro-3-formyl-1H-pyrazolopyrimidin-6(5H)-one (VI) with two mol of quaternary salts furnishes the corresponding cyanine dyes (VII).The structural assignments of all cyanine dyes synthesised are based on their elemental analyses and spectral data.
