6-(1,3-Dioxoindan-2-ylidenemethyl)-1,2,2,4-tetramethyl-1,2-dihydro- and 1,2,3,4-Tetrahydroquinolines

6-Formyl-1,2,2,4-tetraalkyldi- and -tetrahydroquinolines have been synthesized by the Vilsmeier reaction and they are readily condensed with 1,3-indanedione to give 2-hetarylidene-1,3-indanediones. The latter exist as complexes with charge transfer from the quinoid structure of the heterocyclic fragment.