Rhodium(III)-Catalyzed C-H/N-H Alkyne Annulation of Nonsymmetric 2-Aryl (Benz)imidazole Derivatives: Photophysical and Mechanistic Insights.

Rhodium(III) catalysis enabled C-H/N-H alkyne annulation of nonsymmetric imidazole derivatives. This study encompasses the synthesis of imidazoles from a naturally occurring quinoidal compound and their use for the preparation of rigid π-extended imidazole derivatives with outstanding fluorescence. Our study also brings to light the photophysical aspects and the mechanism of the reaction studied via computational calculations. This method provided an efficient and versatile tool for the synthesis of fluorescent compounds with a wide range of chemical and biological applications.

Design of hybrid molecules as antimycobacterial compounds: Synthesis of isoniazid-naphthoquinone derivatives and their activity against susceptible and resistant strains of Mycobacterium tuberculosis.

Isoniazid-naphthoquinone hybrids were synthesized and evaluated against a susceptible (H37Rv) strain and two isoniazid-resistant strains (INHR1 and INHR2) of Mycobacterium tuberculosis. The antimycobacterial activity of the derivatives was determined based on the resazurin microtiter assay and their cytotoxicity in adhered mouse monocyte macrophage J774.A1 cells (ATCC TIB-67). Of the twenty-two compounds evaluated against the three strains of M. tuberculosis, twenty-one presented some activity against the H37Rv and INHR1 (katG S315T) or INHR2 (inhA C(-5)T) strains. Compounds 1a, 2a, and 8a were effective against the INHR1 strain, and compounds 1a, 1b, 2a, 3a, 5a, 5b and 8a were effective against the INHR2 strain, with MICs in the range of 3.12-6.25 µg/mL. Compounds 1b and 5b were the most active against H37Rv, with MIC of 0.78 µg/mL. Based on the selectivity index, 1b and 5b can be considered safe as a drug candidate compounds. These results demonstrate that quinoidal compounds can be used as promising scaffolds for the development of new anti-TB drugs and hybrids with activity against M. tuberculosis-susceptible and INH-resistant strains.

Crystal structure of (±)-3-[(benzo[d][1,3]dioxol-5-yl)meth-yl]-2-(3,4,5-tri-meth-oxy-phen-yl)-1,3-thia-zolidin-4-one.

In the title thia-zolidine-4-one derivative, C20H21NO6S, the central thia-zolidine ring is essentially planar (r.m.s. deviation for all non-H atoms = 0.0287 Å) and forms a dihedral angle of 88.25 (5)° with the meth-oxy-substituted benzene ring and 74.21 (4)° with the 1,3-benzodioxole ring. The heterocyclic ring (with two O atoms) fused to benzene ring adopts an envelope conformation with the non-ring-junction C atom as the flap. In the crystal, the mol-ecules are linked into chains along [001] through weak C-H⋯O inter-actions, forming R (4) 4(28) edge-fused rings.

Synthesis, structure-activity relationships (SAR) and in silico studies of coumarin derivatives with antifungal activity.

The increased incidence of opportunistic fungal infections, associated with greater resistance to the antifungal drugs currently in use has highlighted the need for new solutions. In this study twenty four coumarin derivatives were screened in vitro for antifungal activity against strains of Aspergillus. Some of the compounds exhibited significant antifungal activity with MICs values ranging between 16 and 32 µg/mL. The structure-activity relationships (SAR) study demonstrated that O-substitutions are essential for antifungal activity. It also showed that the presence of a short aliphatic chain and/or electron withdrawing groups (NO(2) and/or acetate) favor activity. These findings were confirmed using density functional theory (DFT), when calculating the LUMO density. In Principal Component Analysis (PCA), two significant principal components (PCs) explained more than 60% of the total variance. The best Partial Least Squares Regression (PLS) model showed an r2 of 0.86 and q2(cv) of 0.64 corroborating the SAR observations as well as demonstrating a greater probe N1 interaction for active compounds. Descriptors generated by TIP correlogram demonstrated the importance of the molecular shape for antifungal activity.

5-Chloro-quinolin-8-yl furan-2-carboxyl-ate.

In the title compound, C14H8ClNO3, the central ester CO2 group is twisted away from the quinoline and furoyl rings by 57.46 (5) and 2.0 (1)°, respectively. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, forming chains in [001].

2,4,6-Trinitro-phenyl 4-chloro-benzoate.

In the title benzoate derivative, C13H6ClN3O8, the planes of the benzene rings form a dihedral angle of 63.46 (5)°. The dihedral angles between the benzene ring and its nitro groups are 12.78 (16)° for the first ortho, 28.4 (4) and 17.4 (4)° for the second (disordered) ortho and 3.58 (16)° for the para nitro group. The central ester moiety, -C-(C=O)-O-, is essentially planar (r.m.s. deviation for all non-H atoms = 0.0229 Å) and forms dihedral angles of 7.37 (14)° with the chloro-substituted benzene ring and 69.85 (6)° with the trinitro-substituted benzene ring. One of the nitro groups was refined as disordered over two sets of sites with fixed site occupancies of 0.61 and 0.39. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional network.

4-Formyl-2-nitro-phenyl 4-bromo-benzoate.

In the title compound, C14H8BrNO5, the benzene rings form a dihedral angle of 62.90 (7)°. The central ester group is twisted away from the nitro-substituted and bromo-substituted rings by 71.67 (7) and 8.78 (15)°, respectively. The nitro group forms a dihedral angle of 7.77 (16)° with the benzene ring to which it is attached. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, forming C(12) chains which run along [001]. Halogen-halogen inter-actions [Br⋯Br = 3.523 (3) Å] within the chains stabilized by C-H⋯O inter-actions are observed.

4-Formyl-2-nitro-phenyl 2-chloro-benzoate.

In the title compound, C14H8ClNO5, the benzene rings form a dihedral angle of 19.55 (9)°. The mean plane of the central ester group [r.m.s. deviation = 0.024 Å] forms dihedral angles of 53.28 (13) and 36.93 (16)°, respectively, with the nitro- and chloro-substituted rings. The nitro group forms a dihedral angle of 19.24 (19)° with the benzene ring to which it is attached. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming C(7) chains, which run along [100].

Dimethyl 2-[(acridin-9-yl)methyl-idene]malonate.

In the title compound, C(19)H(15)NO(4), the acridine system is essentially planar (r.m.s. deviation = 0.015 Å). The crystal packing exhibits π-π inter-actions between pairs of centrosymmetric mol-ecules, one of them between the central heterocyclic rings and others between the outer benzene rings of the acridine systems, with centroid-centroid distances of 3.692 (1) and 3.754 (1) Å, respectively. These pairs are further linked by additional π-π inter-actions along the a-axis direction through one of the two outer benzene ring of neighboring mol-ecules, with a centroid-centroid distance of 3.642 (2) Å.

1,3-Azoles from ortho-naphthoquinones: synthesis of aryl substituted imidazoles and oxazoles and their potent activity against Mycobacterium tuberculosis.

Twenty-three naphthoimidazoles and six naphthoxazoles were synthesised and evaluated against susceptible and rifampicin- and isoniazid-resistant strains of Mycobacterium tuberculosis. Among all the compounds evaluated, fourteen presented MIC values in the range of 0.78 to 6.25 µg/mL against susceptible and resistant strains of M. tuberculosis. Five structures were solved by X-ray crystallographic analysis. These substances are promising antimycobacterial prototypes.

Redetermination of 4-cyano-pyridine N-oxide.

In the title pyridine N-oxide derivative, C(6)H(4)N(2)O, the 4-cyano substituent almost lies in the mean plane of the pyridine ring (r.m.s deviation of all non-H atoms = 0.004 Å). This redetermination results in a crystal structure with significantly higher precision [N-O bond length is 1.2997 (15) compared with 1.303 (5) Šin the original] than the original determination, which was recorded using the multiple-film technique and visually estimated intensities [Hardcastle et al. (1974 ▶). J. Cryst. Mol. Struct.4, 305-311]. The crystal structure features weak C-H⋯O and C-H⋯N inter-actions, which lead to the formation of chains that inter-sect each other parallel to (001).

Ethyl 2-(3-phenyl-thio-ureido)-5,6-di-hydro-4H-cyclo-penta-[b]thio-phene-3-carboxyl-ate.

In the title compound, C(17)H(18)N(2)O(2)S(2), the angle between the mean plane defined by the atoms of the 5,6-dihydro-4H-cyclo-penta-[b]thio-phene moiety (r.m.s. deviation = 0.19 Å) and the phenyl ring is 72.8°(2). The mol-ecular conformation is stabilized by an intra-molecular N-H⋯O inter-action, which generates an S(6) ring motif. In the crystal, pairs of N-H⋯S hydrogen bonds link the mol-ecules to form inversion dimers with an R(2) (2)(8) ring motif.

Tropane alkaloids from Erythroxylum caatingae Plowman.

Three tropane alkaloids, 1-3, were isolated from Erythroxylum caatingae, i.e., 6ß-benzoyloxy-3α-[(4-hydroxy-3,5-dimethoxybenzoyl)oxy]tropane (1), a new tropane alkaloid, along with the known alkaloids 3α,6ß-dibenzoyloxytropane (2) and 6ß-benzoyloxy-3α-[(3,4,5-trimethoxybenzoyl)oxy]tropane (catuabine B; 3). Their structures were determined by 2D- ((1) H and (13) C) NMR. By LC/ESI-MS/MS analysis of the fractions of alkaloids 1-3, it was possible to detect five more alkaloids, 4-8, two of these, 4 and 8, possibly being new natural products. X-Ray crystallography of the chloride derivate of 1, i.e., 6ß-benzoyloxy-3α-(4-hydroxy-3,5-dimethoxybenzoyloxy)tropane hydrochloride (1a) confirmed the structure of 1. Cytotoxicity was tested against the cell lines HEp-2, NCI-H292, and KB for the MeOH extract and alkaloid 3, and antitumor activity was tested against Sarcoma 180 only for the MeOH extract.

4-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)benzoic acid: X-ray and DFT-calculated structure.

In the title compound, C(11)H(7)NO(4), there is a dihedral angle of 45.80 (7)° between the planes of the benzene and maleimide rings. The presence of O-H···O hydrogen bonding and weak C-H···O interactions allows the formation of R(3)(3)(19) edge-connected rings parallel to the (010) plane. Structural, spectroscopic and theoretical studies were carried out. Density functional theory (DFT) optimized structures at the B3LYP/6-311 G(d,p) and 6-31++G(d,p) levels are compared with the experimentally determined molecular structure in the solid state. Additional IR and UV theoretical studies allowed the presence of functional groups and the transition bands of the system to be identified.

Solid dispersions of imidazolidinedione by PEG and PVP polymers with potential antischistosomal activities.

Solid dispersions have been used as a strategy to improve the solubility, dissolution rate, and bioavailability of poor water-soluble drugs. The increase of the dissolution rate presented by (5Z)-3-(4-chloro-benzyl)-5-(4-nitro-benzylidene)-imidazolidine-2,4-dione (LPSF/FZ4) from the solid dispersions is related to the existence of intermolecular interactions of hydrogen bond type (>N-H···O<) between the amide group (>N-H) of the LPSF/FZ4 and the ether group (-O-) of the polyethyleneglycol polymer, or the carbonyl (C=O) of the polyvinylpyrrolidone polymer (PVP). The intensity of these interactions is directly reflected in the morphology acquired by LPSF/FZ4 in these systems, where a new solid phase, in the form of amorphous aggregates of irregular size, was identified through scanning electron microscopy and confirmed in the characterizations achieved using X-ray diffraction and thermal analysis of DSC. The solid dispersions with the polymer PVP, in higher concentrations, were revealed to be the best option to be used in the formulations of LPSF/FZ4 in both theoretical and experimental studies.

4-Methyl-phenyl 4-bromo-benzoate.

In the title compound, C(14)H(11)BrO(2), an ester formed from the reaction of 4-methyl-phenol with 4-bromo-benzoyl-chloride, the dihedral angle between the benzene rings is 54.43 (7)°, indicating a twist in the mol-ecule. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into supra-molecular layers in the bc plane, and these are connected along the a axis by Br⋯Br contacts [3.6328 (5) Å].

cis-Bis{1,1-dibenzyl-3-[(furan-2-yl)carbon-yl]thio-ureato-κO,S}nickel(II).

In the title compound, [Ni(C(20)H(17)N(2)O(2)S)(2)], the Ni(II) atom is coordinated by the S and O atoms of two 1,1-dibenzyl-3-[(furan-2-yl)carbon-yl]thio-ureate ligands in a distorted square-planar geometry. The two O and two S atoms are mutually cis to each other. The Ni-S and Ni-O bond lengths lie within the range of those found in related structures. The dihedral angle between the planes of the two chelating rings is 20.33 (6)°.

cis-Bis[1,1-dibenzyl-3-(furan-2-yl-carbonyl)thio-ureato-κO,S]copper(II).

In the title compound, [Cu(C(20)H(17)N(2)O(2)S)(2)], the Cu(II) atom is coordinated by the S and O atoms of two 1,1-dibenzyl-3-(furan-2-ylcarbon-yl)thio-ureate ligands in a distorted square-planar geometry. The two O and two S atoms are mutually cis to each other. The Cu-S and Cu-O bond lengths lie within the ranges of those found in related structures. The dihedral angle between the planes of the two chelating rings is 26.15 (6)°.

1-(4-Bromo-phen-yl)-2-ethyl-sulfinyl-2-(phenyl-selan-yl)ethanone monohydrate.

In the title hydrate, C(16)H(15)BrO(2)SSe·H(2)O, the sulfinyl O atom lies on the opposite side of the mol-ecule to the Se and carbonyl O atoms. The benzene rings form a dihedral angle of 51.66 (17)° and are splayed with respect to each other. The observed conformation allows the water mol-ecules to bridge sulfinyl O atoms via O-H⋯O hydrogen bonds, generating a linear supra-molecular chain along the b axis; the chain is further stabilized by C-H⋯O contacts. The chains are held in place in the crystal structure by C⋯H⋯π and C-Br⋯π inter-actions.

2-Amino-4,5,6,7-tetra-hydro-benzo[b]thio-phene-3-carbonitrile.

The title compound, C(9)H(10)N(2)S, was synthesized according to Gewald procedures by the reaction of cyclo-hexa-none with malonitrile and sulfur in the presence morpholine. The cyclo-hexane ring adopts a half-chair conformation and the thio-phene ring is essentially planar (r.m.s. deviation = 0.05 Å). The crystal packing is stabilized by two inter-molecular N-H⋯N hydrogen bonds, which link the mol-ecules into centrosymmetric rings with graph-set motif R(2) (2)(12).