Synthesis and Optical Properties of π-Conjugated Azulenes.

The Knoevenagel condensation of azulenyl ketones with malononitrile resulted in the synthesis of π-conjugated 1-mono- and 1,3-bis(phenyldicyanovinyl)azulenes, and the Kumada cross-coupling reaction of bromazulenes with PhMgBr gave 1-mono- and 1,3-biphenylazulene. The electronic spectra of dicyanovinylated azulenes showed strong absorption bands of intramolecular charge transfer in the visible region, as well as significant bathochromic shifts of the absorption maxima of phenylazulenes. [ABSTRACT FROM AUTHOR]