New derivatives of 2,7‐naphthyridine‐3‐carboxylic acid were synthesized. We report the hydrolysis, chlorination, alkylation, and amination of the 2,7‐naphthyridine esters 1, 2. A series of Schiff's bases 8a, 8b, 8c, 8d, 8e, 8f, 8g, 8h, 8i, 8j, 9a, 9b, 9b', 9c, 9d, 9e were produced by treating the obtained hydrazides 6 and 7 with aromatic aldehydes. The anticancer activities of the obtained derivatives were examined. Eighteen of the 24 newly synthesized compounds were qualified by the National Cancer Institute NCI (Bethesda, MD, USA) for in vitro screening against 60 different human tumor cell lines. The most active compound 8i was evaluated against a 60‐cell panel at five concentration levels and proved to be most sensitive towards central nervous system cancer (SF‐539), with GI50 = 0.70 µmol, total growth inhibition = 5.41 µmol, and LC50 = 53.7 µmol.

Pyrrolo[3,4-c]pyridine is one of the six structural isomers of the bicyclic ring system containing a pyrrole moiety fused to a pyridine nucleus. The broad spectrum of pharmacological properties of pyrrolo[3,4-c]pyridine derivatives is the main reason for developing new compounds containing this scaffold. This review presents studies on the biological activity of pyrrolo[3,4-c]pyridines that have been reported in the scientific literature. Most of these derivatives have been studied as analgesic and sedative agents. Biological investigations have shown that pyrrolo[3,4-c]pyridines can be used to treat diseases of the nervous and immune systems. Their antidiabetic, antimycobacterial, antiviral, and antitumor activities also have been found.

Marine and terrestrial environments are rich sources of various bioactive substances, which have been used by humans since prehistoric times. Nowadays, due to advances in chemical sciences, new substances are still discovered, and their chemical structures and biological properties are constantly explored. Drugs obtained from natural sources are used commonly in medicine, particularly in cancer and infectious diseases treatment. Naphthyridines, isolated mainly from marine organisms and terrestrial plants, represent prominent examples of naturally derived agents. They are a class of heterocyclic compounds containing a fused system of two pyridine rings, possessing six isomers depending on the nitrogen atom’s location. In this review, biological activity of naphthyridines obtained from various natural sources was summarized. According to previous studies, the naphthyridine alkaloids displayed multiple activities, i.a., antiinfectious, anticancer, neurological, psychotropic, affecting cardiovascular system, and immune response. Their wide range of activity makes them a fascinating object of research with prospects for use in therapeutic purposes.

: 2,7-Naphthyridine is one of the six structural isomers of pyridopyridine. Biological investigations have shown that these compounds have a broad spectrum of activity. They have been found to have antitumor, antimicrobial, analgesic and anticonvulsant effects. The broad spectrum of biological activity of 2,7-naphthyridine derivatives is the main reason for the preparation of new compounds containing this scaffold. This review aims to present various methods of obtaining 2,7-naphthyridine analogs. Compounds containing a 2,7-naphthyridine moiety can be synthesized from a variety of substrates and may be classified into four main categories: those derived from acyclic compounds, from quinoline derivatives, from pyridine derivatives, and from other compounds. Most of them were obtained by the cyclocondensation or intramolecular cyclization of pyridine derivatives. Cyclocondensations of non-cyclic substrates also produced 2,7-naphthyridine derivatives. Tricyclic benzo[2,7]naphthyridines were prepared from quinolines. The 2,7-naphthyridine scaffold has also been synthesized by the rearrangement of pyrrolo[3,4-c]pyridines, pyrano[3,4-c]pyridines or thiopyrano[3,4-c]pyridines.

Fused pyridine derivatives R 0450 Synthesis, Structure, and Pharmacological Screening of 2,7-Naphthyridine Derivatives. -A method for the rearrangement of pyrrolo[3,4-c]pyridines (III) and (VI) into the corresponding 2,7-naphthyridines is developed. Derivative (IV) demonstrates growth inhibition of the ovarian cancer cell line IGROV1. -(WAGNER*, E.; WOJCICKA, A.; BRYNDAL, I.; LIS, T.; Pol.

This review presents most of the literature data about synthesis and biological activity of pyridopyridazine derivatives. There are six structural isomers of the bicyclic ring system containing pyridine moiety condensed with pyridazine nucleus. Pyridopyridazine derivatives show antitumor, antibacterial, analgesic and diuretics activities. The derivatives have been identified as the selective phosphodiesterase 5 and phosphodiesterase 4 inhibitors. Pyridopyridazines are novel class of GABA-A receptor benzodiazepine binding site ligands. Some of pyrido[3,2-c]pyridazine derivatives possess molluscicidal activity and can be used as biodegradable agrochemicals. The broad spectrum of biological activity of pyridopyridazine derivatives is the main reason for the preparation of new compounds containing this scaffold.

The synthesis of novel derivatives containing the quinazolinone-4 moiety is described. 3-Amino-2(1H)-tioxo-4(3H)-quinazolinone (1) forms a sodium salt 2, which was subjected to reaction with dicarboxylic acid chlorides such as chloroformyl ethyl formate and malonyl chloride, leading to the corresponding ester 3 and acid 4, respectively. 3-Amino-2-ethoxycarbonylmethylthio-4(3H)-quinazolinone (5) was acylated or ammonolyzed and products of various chemical structure were obtained. The chemical structures 3, 4, 6-12, and 14-18 were identified by the results of elemental analysis and their IR, 1 H NMR, and mass spectra.

Derivatives of pyrido[3,4-d]pyridazine, namely, 1-hydroxy-5-methyl-7-phenylpyrido[3,4-d]pyridazin-4(3H)-one dimethylformamide monosolvate, C14H11N3O2·C3H7NO (2), ethyl [1-(2-ethoxy-2-oxoethoxy)-5-methyl-4-oxo-7-phenyl-3,4-dihydropyrido[3,4-d]pyridazin-3-yl]acetate, C18H17N3O4 (3), and ethyl [(5-methyl-4-oxo-7-phenyl-3,4-dihydropyrido[3,4-d]pyridazin-1-yl)oxy]acetate, C22H23N3O6 (4), were synthesized with the aim of discovering new potential biologically active agents. The properties of all three derivatives were characterized by 1H NMR, 13C NMR and FT–IR spectroscopic analysis. All the crystals were obtained by a solvent diffusion method from dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) and characterized by single-crystal X-ray diffraction. The collected X-ray data revealed that the crystals of 2 and 4 belong to the triclinic space group P\overline{1}, whereas the crystal of 3 belongs to the monoclinic space group P21/c. The presented derivatives crystallized with one molecule in the asymmetric unit, but only compound 2 crystallized as a solvate with DMF. Structure analysis showed that the molecule of 2 exists as its amide–imidic acid tautomer and that O-alkylation occurred before N-alkylation during the synthesis of the mono- and disubstituted derivatives, i.e. 3 and 4, respectively. The molecular geometries of the 5-methyl-7-phenylpyrido[3,4-d]pyridazine core within the studied derivatives differ in the mutual orientation of the rings. The interplanar angles between the heterocyclic ring and the bound aromatic ring are 1.71 (7), 18.16 (3) and 3.1 (1)° for 2, 3 and 4, respectively. The potential cytotoxicity of these compounds was evaluated against one normal (HaCat) and four human cancer cell lines (A549, DU145, MDA-MB-231 and SKOV-3).