The title compound was synthesized either by introduction of another pyridine ring into 3-(2-pyridyl)-1,2,3,8-tetrahydroazulen-1-one or by Stille and Negishi double cross-coupling reactions of 1,3-dihaloazulenes with the corresponding 2-pyridyl reagents.
Pyridylazulenes: Synthesis, Color Changes, and Structure of the Colored Product
method for the synthesis of 1- and 2-pyridylazulenes, and of 1,3-dipyridylazulenes, is described. Color and spectral changes of these pyridylazulenes upon the addition of either acid or metal ions were investigated in detail. The color changed from blue to red upon the addition of trifluoroacetic acid or soft metal ions, depending on the substitution patterns of the pyridyl group on the azulene skeleton