ChemInform Abstract: Synthesis of Pyrrolo(2,3-g)benzothiazoles and of Polymethine Dyes Derived from Them.

ChemInform Abstract

The title compounds (VI) serve as starting materials for the synthesis of the asymmetric polymethine dyes (VII)-(IX). These dyes absorb at longer wavelengths than their furo- or thieno-(2,3-g) analogues. Substitution of the hydrogen atom attached to the pyrrole nitrogen atom by a methyl group - cf. (VIIa) and its N-methyl derivative (VIIb) - causes a further bathochromic shift of the absorption maximum. These dyes may be applied as photosensitizers.