Synthesis of Some Benzo[b][1,6]naphthyridines and Benzo[b][1,7]naphthyridines

Abstract

Pfitzinger (1-benzylpiperidin-4-one with 7-methylisatin) and Friedlander (3-aminopyridine-4-carbaldehyde with 2-methylcyclohexanone) syntheses, respectively, were used to prepare the title 'azaacridines' containing a methyl substituent peri to the central nitrogen. Oxidation of this group gave the corresponding aldehyde and carboxylic acid. In the [1,6] case, especially, the 10-position was also easily oxidized to give acridone analogues. Nitration occurred exclusively in the benzenoid rings.

Synthesis of Novel Benzo[b][1,6]naphthyridine Derivatives and Investigation of Their Potential as Scaffolds of MAO Inhibitors

“…The synthesis of benzonaphthyridines is mainly based on ring-closing methods, which are used in the synthesis of quinolines. The use of Frindler [ 22 ], Pfitzinger [ 23 ] and Niementowski [ 24 ] reactions, as well as synthesis based on 2-ethynylquinolyl-3-carbaldehydes [ 25 ] and aminopyridines [ 26 ], makes it possible to obtain derivatives containing functional groups in various positions of the tricyclic system.…”

Synthesis and Antitumor Properties of N-[2-(Dimethylamino)ethyl]carboxamide Derivatives of Fused Tetracyclic Quinolines and Quinoxalines: A New Class of Putative Topoisomerase Inhibitors

“…Analyses indicated by symbols of the elements were within ±0.4% of the theoretical. 7-Methylisatin, benzothiophen-3(2 H )-one, and 3-acetoxy-1-acetylindole were prepared as reported. Ethyl salicylate and ethyl bromoacetate were reacted as reported and the reaction worked up by an alternative procedure to give ethyl O -carbethoxymethylsalicylate.…”

“…This was prepared by a modification of a literature method, and reactions with 26 − 29 gave 30 − 33 . Two reactions in this series were also carried out with 7-methylisatin ( 25 ), condensing this with 28 and 29 to give the tetracycles 34 and 35 . Many variations of base catalysis have been employed in the Pfitzinger reaction .…”