Bakhodir Tashkhodjaev

8β-Acet­oxy-14α-benzo­yloxy-N-ethyl-3α,10β,13β,15α-tetra­hydr­oxy-1α,6α,16β-trimeth­oxy-4β-(methoxy­methyl­ene)aconitane: aconifine from Aconitum karakolicum Rapaics

The title compound, C34H47NO12, is the norditerpenoid alkaloid aconifine isolated from the leaves and tubers of Aconitum karakolicum Rapaics. It has a lycoctonine carbon skeleton and contains four six-membered rings and two five-membered rings; its geometry is similar to that observed in other lycoctonine-type diterpenoid alkaloids. There are two intramolecular O—H⋯O hydrogen bonds which close five- and seven-membered pseudo-rings, respectively. In the crystal, two intermolecular O—H⋯O hydrogen bonds cross-link the molecules into double chains along the a axis.

2-Methyl-4-oxo-6,7,8,9-tetrahydro­thieno[2′,3′:4,5]pyrimidino­[1,2-a]pyridine-3-carboxylic acid

There are two independent molecules in the asymmetric unit of the title compound, C12H12N2O3S. With the exception of the methylene groups, a mean plane fitted through all non-H atoms of each molecule has an r.m.s. deviation of 0.035 Å for one molecule and 0.120 Å for the second. In one of the independent molecules, the methylene groups was refined using a disorder model with an occupancy ratio of 0.53:0.47 (14). Each molecule features an intramolecular O—H⋯O hydrogen bond, which generates an S(7) ring.

Synthesis, Tautomeric States and Crystal Structure of (Z)-Ethyl 2-Cyano-2-(3H-Quinazoline-4-ylidene) Acetate and (Z)-Ethyl 2-Cyano-2-(2-Methyl-3H-Quinazoline-4-ylidene) Acetate

The new compounds (Z)-ethyl 2-cyano-2-(3H- and 2-methyl-3H-quinazoline- 4-ylidene) acetate (1 and 2, respectively) were synthesized by multi-step reactions. The structures in a solution have been determined by 1H-NMR spectroscopy and in the crystal form by X-ray analysis. Molecule 1 crystallized in a primitive monoclinic cell, space group Р21/c. The cell dimensions are a=7.970(6) Å, b=7.061(2) Å, c=20.537(7) Å, β=97.69(5)°, V=1145.3(10) Å3. Molecule 2 crystallized in a triclinic cell, space group P1, the cell dimensions are a=8.196(5) Å, b=8.997(6) Å, c=9.435(4) Å, α=74.22(4)°, β=89.75(4)°, γ=74.07(5)°, V=641.9(6) Å3. In both compounds the presence of intramolecular NH---O=C hydrogen bonding between the nitrogen atom in position 3 of the quinazoline ring and a carbonyl group of the ethyl cyanoacetate residue was proven by quantum-chemical, 1H-NMR and X-ray methods.

Benzazoles: I. Regioselective arylsulfonylation of benzimidazol-2-amine

Benzimidazol-2-amine reacted with arenesulfonyl chlorides in the presence of triethylamine in regioselective fashion at the endocyclic nitrogen atom, the exocyclic amino group remaining intact. The yields of 1-arylsulfonylbenzimidazol-2-amines depend on the electronic properties of substituents in the benzene ring of arenesulfonyl chlorides.

1,2,4-Thiadiazol derivatives of cytisine alkaloid: solvate formation and phase transitions

Abstract1,2,4-Thiadiazol derivatives of cytisine alkaloid—N-(3-methylthio-1,2,4-thiadiazol-5-yl-aminocarbonylmethyl) (1), N-(3-ethylthio-1,2,4-thiadiazol-5-yl-aminocarbonylmethyl) (2), N-(3-hexylthio-1,2,4-thiadiazol-5-yl-aminocarbonylmethyl) (3) cytisine have been crystallized from different solvents and by X-ray and TG–DSC method were studied. By X-ray analysis the structures of the crystal solvate of 2 with dioxane have been determined. By topology represented solvate belongs to tabulate type. In the crystal structure two conformers of the host molecules were determined. By TG–DSC method has been shown, that methyl-, ethyl-, and hexyl cytisine derivatives can exist in two phase forms. But, unlike methyl- and ethyl-derivatives, hexyl-derivative of cytisine not form inclusion compounds.

2-n-Butyl-6-chloro-1-(2,4-dimethyl-phenyl-sulfon-yl)-1H-benzimidazole-2-n-butyl-5-chloro-1-(2,4-dimethyl-phenyl-sulfon-yl)-1H-benzimidazole (0.759/0.241).

The title compound, 0.759C19H21ClN2O2S·0.241C19H21ClN2O2S, was synthesized by arylsulfonylation of 2-n-butyl-5-chloro-1H-benzimidazole in the presence of triethylamine. The crystal structure is composed of two molecules, 2-n-butyl-6-chloro-1-(2,4-dimethylphenylsulfonyl)-1H-benzimidazole and 1-(2,4-dimethylphenylsulfonyl)-2-n-butyl-5-chloro-1H-benzimidazole, in the refined ratio of 0.759 (4):0.241 (4) disordered at the same position in the unit cell. The molecule has three essentially planar fragments viz. benzimidazole, dimethylbenzene and n-butyl (r.m.s. deviations of 0.009, 0.024 and 0.003 Å, respectively). The angle between the benzimidazole and dimethylbenzene fragments is 86.0 (1)°. In the crystal, pairs of intermolecular C—H⋯π interactions form centrosymmetrical dimers, which are linked by weak intermolecular C—H⋯O hydrogen bonds.

(4-Nitrophenyl)(1,2,3,9-tetrahydro-pyrrolo[2,1-b]quinazolin-3-yl)methanol monohydrate.

In the crystal structure of the title compound, C18H17N3O3·H2O, the molecules are linked by O—H⋯O and O—H⋯N hydrogen bonds, resulting in a chain along the a axis. The crystal structure is stabilized by weak intermolecular C—H⋯π (ring) hydrogen bonds and aromatic π⋯π stacking interactions [centroid–centroid distance = 3.902 (1) Å] between the pyrimidino rings of the quinazoline system. The tricyclic quinazoline fragment is almost planar (rms deviation = 0.0139 Å) with the two methylene C atoms of the pyrrolo ring deviating by 0.148 (2) and −0.081 (3) Å from the plane through the other atoms. The 4-nitrophenyl ring makes a dihedral angle of 12.55 (7)° with the tricyclic ring system.

(E)-3-[4-(Dimethyl­amino)­benzyl­idene]-2,3-di­hydro-1H,9H-pyrrolo­[2,1-b]quinazolin-9-one

The title compound, C20H19N3O, was obtained by condensation of 2,3-dihydro-1H,9H-pyrrolo[2,1-b]quinazolin-9-one (alkaloid deoxyvasicinone, isolated from Peganum Harmala) with 4-(dimethylamino)benzaldehyde in the presence of sodium methoxide. The 2,3-dihydro-1H,9H-pyrrolo[2,1-b]quinazolin-9-one part of the molecule is roughly planar (r.m.s. deviation = 0.0178 Å) and is essentially coplanar with the benzilidene ring (r.m.s. deviation = 0.0080 Å), forming a dihedral angle of 5.0 (1)°. The crystal structure is stabilized by two aromatic π–π stacking interactions observed between the benzene rings of neighboring molecules [centroid–centroid distance = 3.7555 (19) Å.

9-Furfuryl­idene-2,3-dimethyl-6,7,8,9-tetrahydro-4H-­thieno[2′,3′:4,5]pyrimidino[1,2-a]pyridin-4-one

The title compound, C17H16N2O2S, was obtained by condensation of 2,3-dimethylthieno[2′,3′:4,5]pyrimidino[1,2-a]pyridin-4-one with furfural in the presence of sodium hydroxide. One of the methylene groups of the tetrahydropyrido ring is disordered over two positions in a 0.87 (1):0.13 (1) ratio. The thieno[2,3-d]pyrimidin-4-one unit and the furan ring are both planar (r.m.s. deviation = 0.535 Å), and coplanar with each other, forming a dihedral angle of 5.4 (1)°. Four weak intermolecular hydrogen bonds (C—H⋯O and C—H⋯N) are observed in the structure, which join molecules into a network parallel to (101).

(1-Phenyl-1H-1,2,3-triazol-4-yl)methyl pyridine-3-carboxyl­ate

In the title compound, C15H12N4O2, the dihedral angle between the planes of the nicotinoyloxy fragment and triazole ring is 88.61 (5)°. The dihedral angle between the planes of triazole and benzene rings is 16.54 (11)°. The crystal structure is stabilized by intermolecular C—H⋯N, C—H⋯O and C—H⋯π(triazole) hydrogen bonds and aromatic π–π stacking interactions between the benzene and triazole rings [centroid–centroid distance = 3.895 (1) Å]