The action of the two Vilsmeier reagents from dimethylformamide and phosphoryl chloride or thionyl chloride on 2-amino-3-picoline, 3-amino-4-picoline, and 4-amino-3-picoline is reported. The first reagent with 3-amino-4-picoline gave 3-formyl-1,6-diazaindene (pyrrolo[2,3-c]pyridine-3-carbaldehyde) and NN-dimethyl-N′-(4-methyl-3-pyridyl)formamidine, and with 3-amino-2-methylquinoline yielded 3-formyl-1,4-diazabenz[f]-indene(pyrrolo[3,2-b]quinoline-3-carbaldehyde). Some modifications of the aldehydes were investigated; 3-(NN-dimethylaminomethyl)-1,6-diazaindene was prepared.