(RS)-2-Oxo-4-(1-phenyl­ethyl­amino)-1,2-dihydro­quinoline-3-carb­oxy­lic acid

The mol­ecular structure of the title compound, C18H16N2O3, does not differ in the crystals of the racemic mixture, (I), and the pure enantiomer, (II). In their crystal structures, inversion dimers occur in (I) via N—H⋯O hydrogen bonds and infinite chains in (II) also via N—H⋯O hydrogen bonds

Methyl 2-(4-hy­droxy-1-methyl-2-oxo-1,2-dihydro­quinolin-3-yl)acetate

In the title compound, C13H13NO4, the bicyclic quinolone fragment and the ester group are approximately orthogonal, making a dihedral angle of 83.3 (2)° and an intramolecular C—H⋯O interaction occurs. In the crystal, inter­molecular O—H⋯O hydrogen bonding generates a zigzag chain along the c axis

Ethyl 2-(4-hydr­oxy-1-methyl-2-oxo-1,2-dihydro­quinolin-3-yl)acetate

In the title compound, C14H15NO4, the bicyclic fragment and the ester group form a dihedral angle of 86.7 (2)°. Inter­molecular O—H⋯O and C—H⋯O hydrogen bonding connects mol­ecules into a helix along the crystallographic b axis

Ethyl 5-[(1H-benzoimidazol-2-yl)amino­carbon­yl]-4-hydr­oxy-2-methyl-6-oxo-1-propyl-1,6-dihydro­pyridine-3-carboxyl­ate–ethanol–methanol (4/2/1)

The asymmetric unit of the title compound, 4C20H22N4O5·2C2H6O·CH4O, contains two pyridine-3-carboxyl­ate mol­ecules, one ethanol mol­ecule and one methanol mol­ecule disordered about in a centre of symmetry. The pyridinone ring, the carbamide group and the bicyclic fragment in both independent mol­ecules are planar within 0.03 Å due to the formation of intra­molecular O—H⋯O and N—H⋯O hydrogen bonds. The formation of these latter inter­actions also causes the redistribution of the electron density within the hydroxy­pyridone fragment, with the result that some bonds are elongated compared with values in the literature and some others are shorter. In the crystal phase, the pyridine-3-carboxyl­ate mol­ecules form layers parallel to (010), which are inter­linked through hydrogen bonds mediated by the bridging solvate mol­ecules. A terminal ethyl group in one of the mol­ecules is disordered over two sites of equally occupancy

2-Bromo­methyl-N-isopropyl-7,8-dimeth­oxy-1,2-dihydro-1,3-oxazolo[3,2-a]quinoline-4-carboxamide

In the title compound, C18H21BrN2O5, conjugation between the π-donating N—C—O fragment and the π-withdrawing carbonyl group results in considerable redistribution of the electron density within the dihydropyridinol ring. This effect is also promoted by the formation of an intra­molecular N—H⋯O hydrogen bond. The five-membered heterocycle is disordered over two envelope conformations in a 0.35:0.65 ratio

N-Aryl-7-hydroxy-5-oxo-2,3-dihydro-1H,5H-pyrido-[3,2,1-ij]quinoline-6-carboxamides. The Synthesis and Effects on Urinary Output

Continuing a targeted search for new leading structures with diuretic action among tricyclic derivatives of hydroxyquinolines, which are of interest as potential inhibitors of aldosterone synthase, the synthesis of a series of the corresponding pyrido[3,2,1-ij]quinoline-6-carboxanilides was carried out by amidation of ethyl-7-hydroxy-5-oxo-2,3-dihydro-1H,5H-pyrido[3,2,1-ij]quinoline-6-carboxylate with aniline, aminophenols and O-alkylsubstituted analogs with high yields and purity. The optimal conditions of this reaction are proposed; they make it possible to prevent partial destruction of the original heterocyclic ester and thereby avoid formation of specific impurities of 7-hydroxy-2,3-dihydro-1H,5H-pyrido[3,2,1-ij]quinolin-5-one. To confirm the structure of all substances obtained, elemental analysis, nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry were used. Moreover, the peculiarities of their 1H and 13C-NMR spectra, as well as their mass spectrometric behavior under conditions of electron impact ionization, were discussed. The effect of pyrido[3,2,1-ij]quinoline-6-carboxanilides on the urinary function of the kidneys was studied in white rats of both genders by the standard method of oral administration at a dose of 10 mg/kg. Testing was conducted in comparison with hydrochlorothiazide, as well as with structurally close pyrrolo[3,2,1-ij] quinoline-5-carboxanilides studied earlier with the same substituents in the anilide fragments. It was found that addition of one methylene unit to the heterocycle partially hydrogenated and annelated with the quinolone core has a positive impact on biological properties—most of the substances studied exhibit a statistically significant diuretic effect exceeding the activity of not only hydrochlorothiazide, in some cases, but also the action of the structural analogs. The important structural and biological regularities, which are common with pyrroloquinolines and introduced by a chemical modification, were revealed. The importance of the presence in the structure of terminal amide fragments of tricyclic quinoline-3-carboxamides of a 4-methoxy-substituted aromatic ring was particularly marked. The expediency of further study of pyridoquinolines as promising diuretic agents has been shown