ChemInform Abstract: Bridged Cyanine Dyes. Part 3. Zwitterionic Bis‐4‐pyridyl and Cationic Bisdimethylanilino Derivatives.

Abstract Base‐mediated twofold condensation reaction of the cyclic ketones (II) with the (het)aromatic aldehydes (I) or (VIII) yields the bismethylene ketones (III) or (IX).