Interaction of 2-(1H-benzimidazol-2-yl)-thieno[2,3-b]pyridin-3-amines with ortho-Formylbenzoic Acids

We describe a two-stage synthesis of heptacyclic structures, isoindolo[1',2':2,3]pyrido[3",2":4',5']-thieno[3',2':4,5]pyrimido[1,6-a]benzimidazol-6(10bH)-ones, and intermediates, 5,6-dihydropyrido-[3",2":4',5']thieno[3',2':4,5]pyrimido[1,6-a]benzimidazol-6-yl]benzoic acids, as products from the interaction of 3-amino-2-benzimidazolylthieno[2,3-b]pyridines and ortho-formylbenzoic acids. 5,6-Di-hydropyrido[3",2":4',5']thieno[3',2':4,5]pyrimido[1,6-a]benzimidazol-6-yl]benzoic acids were shown to easily oxidize (aromatize) to the corresponding pyrido[3",2":4',5']thieno[3',2':4,5]pyrimido[1,6-a]-benzimidazol-6-yl]benzoic acids. The molecular and crystal structures of 4-(methoxymethyl)-2-methyl-isoindolo-[1',2':2,3]pyrido[3",2":4',5']thieno[3',2':4,5]pyrimido[1,6-a]benzimidazol-6(10bH)-one and 2-[4-(methoxymethyl)-2-methylpyrido[3",2":4',5']thieno[3',2':4,5]pyrimido[1,6-a]benzimidazol-6-yl]- benzoic acid were studied by X-ray crystallography.