Maleate salts of bedaquiline

Bedaquiline is one of two important new drugs for the treatment of drug-resistant tuberculosis (TB). It is marketed in the US as its fumarate salt, but only a few salts of bedaquiline have been structurally described so far. We present here five crystal structures of bedaquilinium maleate {systematic name: [4-(6-bromo-2-methoxyquinolin-3-yl)-3-hydroxy-3-(naphthalen-1-yl)-4-phenylbutyl]dimethylazanium 3-carboxyprop-2-enoate}, C32H32BrN2O2 +·C4H3O4 −, namely, a hemihydrate, a tetrahydrofuran (THF) solvate, a mixed acetone/hexane solvate, an ethyl acetate solvate, and a solvate-free structure obtained from the acetone/hexane solvate by in situ single-crystal-to-single-crystal desolvation. All salts exhibit a 1:1 cation-to-anion ratio, with the anion present as monoanionic hydromaleate and a singly protonated bedaquilinium cation. The maleate exhibits the strong intramolecular hydrogen bond typical for cis-dicarboxylic acid anions. The conformations of the cations and packing interactions in the maleate salts are compared to those of free base bedaquiline and other bedaquilinium salts.

Crystal, molecular structure and Hirshheld surface analysis of 5-hydroxy-3,6,7,8-tetramethoxyflavone

The title compound (systematic name: 5-hydroxy-3,6,7,8-tetramethoxy-2-phenyl-4H-chromen-4-one), C19H18O7, is a flavone that was isolated from a butanol extract of the herb Scutellaria nepetoides M. Pop. The flavone molecule is almost planar, with a dihedral angle between the planes of the benzopyran-4-one group and the attached phenyl ring of 6.4 (4)°. The 5-hydroxy group forms a strong intramolecular hydrogen bond with the carbonyl group, resulting in a six-membered hydrogen-bonded ring. The crystal structure has triclinic (P\overline{1}) symmetry. In the crystal, the molecules are linked by C—H...O hydrogen bonds into a two dimensional network parallel to the ab plane. The Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (53.9%) and H...O/O...H (20.9%) interactions.

Novel One-Pot Synthesis of Methyl 4-Hydroxy-2-thioxo-1,2-dihydroquinoline-3-carboxylate: Synthetic and Crystallographic Studies

A new suitable method of synthesis of methyl 4-hydroxy-2-thioxo-1,2-dihydroquinoline-3-carboxylate by condensation of methyl 2-isothiocyanatobenzoate and methyl malonate is described. The structure of the compound both and by-product methyl 2(methoxycarbonothioylamino)benzoate was confirmed by means of elemental analysis, 1H NMR, 13C NMR, LC/MS and single crystal X-ray diffraction. UV/Vis and IR spectra of compounds are described. The presence of a strong intramolecular hydrogen bond between the hydroxy group and the carbonyl oxygen atom of the ester group in methyl 4-hydroxy-2-thioxo-1,2-dihydroquinoline-3-carboxylate is shown. The crystal structure of product was stabilized through intermolecular hydrogen bonds.

One-Pot Synthesis of Trifluoromethylated Pyrazol-4-yl-pyrrole-2,5-dione Derivatives

Efficient and convenient one-pot, three-component reactions of pyrrolidone, aromatic aldehydes and 1-phenyl-3-trifluoromethyl-5-pyrazolone afforded highly functionalized trifluoromethylated pyrazol-4-ylpyrrole-2,5-dione derivatives in good yields. The effect of solvents on the reaction efficiency and yield was briefly investigated. The structures of products were determined by spectral methods and X-ray diffraction analysis. The latter showed that the products formed have a strong intramolecular hydrogen bond, which made them particularly stable and the corresponding annulated products were not obtained by treatment with dehydrating reagents.

Synthesis, Characterization, and Tautomeric Properties of Some Azo-azomethine Compounds

The primary azo compound 1-(3-formyl-4-hydroxyphenylazo)-4-nitrobenzene reacts with some aliphatic and aromatic diamines and yields the corresponding azo-azomethine compounds. These compounds were characterized by elemental analysis, IR, UV/Vis, and NMR spectroscopy. The primary azo compound exists entirely in the azo form in solution as well as in the solid phase. The tautomeric structure of azo-azomethine compounds heavily depends on the solvent and the substituents. Aliphatic diamine-based compounds favor the enol-imine tautomer while aromatic diamine-based compounds have structures that lie between the two enol-imine and keto-amine tautomers due to a relatively strong intramolecular hydrogen bond. The compounds exhibit positive solvatochromism (bathochromic shift) so that their absorption bands move toward longer wavelengths as the polarity of the solvents increases. In addition, UV/Vis spectrophotometry has shown that the studied compounds have molar extinction coefficients larger than 40000.

(E)-4-Bromo-2-(2-methoxyphenyliminomethyl)phenol

The molecule of the title compound, C14H12BrNO2, is almost planar and the dihedral angle between the planes of the two aromatic rings is 3.8 (2)°. The molecule exists in the crystal structure in the phenol–imine tautomeric form, with the H atom located on O rather than on N. This H atom is involved in a strong intramolecular hydrogen bond.

The crystal structure of 1-(4-chlorophenyl)-3-(4-methylbenzoyl)thiourea

Abstract1-(4-Chlorophenyl)-3-(4-methylbenzoyl)thiourea was synthesized and characterized by IR,1H and 13C NMR, mass spectroscopy and the elemental analysis. The crystal structure was confirmed from single crystal X-ray diffraction data. It crystallizes in the monoclinic space group P21/c with unit cell dimensions a=12.038(3), b=6.330(6), c=18.912(5) Å and β=100.32(3)°. There is a strong intramolecular hydrogen bond of the type N−H...O, with distance N1...O1=2.659(3) Å. The structure is composed of dimers related by inversion centers. The dimers are formed by intermolecular interactions of the type N−H...S with N...S separation of 3.440(2) Å. The mass fragmentation pattern has also been discussed.