Synthesis of Methine Dyes Having Dimethylaminoindolizine Skeleton as an Electron Donor

Abstract

By the reaction of 2-(1-cyano-1-methylthio) methyleneindan-1, 3-dione (1) with 7-dimethylaminoindolizine derivatives (8c, 9a, b), the corresponding substituted compounds (11, 12a, b) were obtained. Novel methine dyes (13-16) exhibiting their absorption maxima in the near-IR region (692-828 nm) were synthesized by the condensation of the compounds (11, 12a, b) with malononitrile in the presence of TiCl₄ and pyridine.