Synthesis, characterization and antitubercular activities of heterocyclic selenosemicarbazones.

Reaction of cyclohexanoneselenosemicarbazone with aldehydes and ketones containing heterocyclic rings (2-oxindole, 6-cholro-2-oxindole, 3-methyl-2-oxindole, isatin, 1-methyl isatin, furfural, pyrrole-2-carboxldehyde) in ethanol yielded, respective, selenosemicarbazones {2-oxindoleselenosemicarbazone (2-HOxsesc,H1L), 6-chloro-2-oxindole selenosemicarbazone (6-ClHOxsesc, H2L), 3-methyl-2-oxindole selenosemicarbazone (3-MeHOxses, H3L), isatinselenosemicarbazone (HIstsesc, H4L), 1-methyl isatinselenosemicarbazone (1-MeHIstsesc, H5L), 2-thiopheneselenosemicarbazone (2-Hthiosesc, H6L), 2-furfuralselenosemicarbazone (2-Hfursesc, H7L) and 2-pyrrole selenosemicarbazone (2-Hpysesc, H8L)}. However the similar reaction with aldehyde containing single aromatic ring (3-chlorobenzaldehyde and 4-chlorobenzaldehyde) formed 1, 2-bis(3-chlorobenzylidiene) hydrazine (A) and 1, 2-bis(4-chlorobenzylidiene) hydrazine (B) rather than selenosemicarbazone. All the synthesized compounds were characterized using IR and NMR (1H, 13C) spectroscopy. Structure of A and B were confirmed by single crystal X-ray crystallography. The synthesized selenosemicarbazones were tested for their anti-tubercular activities and H1L, H3L, H5L and H6L are found to exhibit excellent anti-TB activity. The experimental data will give an opportunity to examine their anti-tubercular activities and identify the lead molecule.

Pseudo-Five-Component Reaction for Diastereoselective Synthesis of Butterfly Shaped Bispiro[Oxindole-Pyrrolidine]s.

A pseudo-five-component reaction involving double decarboxylative 1,3-dipolar cycloaddition of azomethine ylides with olefinic oxindoles for the diastereoselective synthesis of bispiro[oxindole-pyrrolidine]s is developed. The major diastereomers are unique butterfly shaped compounds with a plane of symmetry. Recyclable zeolite HY acid catalyst is used to promote the reaction, and only CO2 and H2O are generated as byproducts.

One-Pot Double [3 + 2] Cycloadditions for Diastereoselective Synthesis of Pyrrolidine-Based Polycyclic Systems.

Sequential inter- and intramolecular [3 + 2] cycloadditions of azomethine ylides are developed for the one-pot and diastereoselective synthesis of highly condensed heterocyclic systems containing pyrrolidine and up to seven stereocenters. It has high synthetic efficiency and operational simplicity, and only water was generated as a byproduct.

Enhancement in anti-tubercular activity of indole based thiosemicarbazones on complexation with copper(I) and silver(I) halides: Structure elucidation, evaluation and molecular modelling.

A series of monomeric tetrahedral complexes of stoichiometry, [MX(HL)(Ph3P)2] (In case of M = Cu, H1L, X = I, 1; Br, 2; Cl, 3; H3L, X = I, 4; Br, 5; Cl, 6; H4L, X = I, 7; Br, 8; Cl, 9 and in case of M = Ag, H1L, X = Cl, 13; Br, 14; H2L, X = Cl, 15, Br 16; H3L, X = Cl, 17, Br, 18) were synthesized by the reaction of copper (I) or silver (I) halides with indole-3-thiosemicarbazone (H1L) or 5-methoxy indole-3-thiosemicarbazone (H2L) or 5-methoxy indole-N1-methyl-3-thiosemicarbazone (H3L), whereas dimers of stoichiometry, [Cu2(µ-X)2(η1-S-H2L)2(Ph3P)2] (X = I, 10; Br, 11; Cl, 12) were obtained by the reaction of copper (I) halides with indole-N1-methyl-3-thiosemicarbazone (HIntsc-N1-Me, H2L). The synthesized complexes were characterized using NMR (1H and 13C) and single crystal X-ray diffraction (H2L, 3, 7, 8, 10, 11 and 13) as well as elemental analysis. Anti- M. tuberculosis activity of ligands (H1L-H4L) and their metal complexes (1-18) were evaluated against M. tuberculosis H37RV strain ATCC 27294. It has been observed that there is unusual enhancement in anti TB activity of these ligands on complexation with copper (I) and silver (I). Molecular modelling studies in the active binding site are also giving complementary theoretical support for the experimental biological data acquired.

Organocatalytic One-Pot Asymmetric Synthesis of Thiolated Spiro-γ-lactam Oxindoles Bearing Three Stereocenters.

The first asymmetric synthesis of spiro-γ-lactam oxindoles bearing three stereocenters is reported. One-pot thiol-Michael/Mannich/lactamization reactions promoted by a recyclable fluorous bifunctional cinchona alkaloid/thiourea organocatalyst afford products in moderate to good yields with up to 95% ee and 6:1 dr.

Stereoselective synthesis of fused tetrahydroquinazolines through one-pot double [3 + 2] dipolar cycloadditions followed by [5 + 1] annulation.

The one-pot [3 + 2] cycloaddition of an azomethine ylide with a maleimide followed by another [3 + 2] cycloaddition of an azide with the second maleimide gives a 1,5-diamino intermediate which is used for a sequential aminomethylation reaction with formaldehyde through [5 + 1] annulation to afford a novel polycyclic scaffold bearing tetrahydroquinazoline, pyrrolidine, pyrrolidinedione, and N-substituted maleimide in stereoselective fashion.

Synthesis and properties of the strained alkene perfluorobicyclo[2.2.0]hex-1(4)-ene.

The title fluoroalkene has been generated by dehalogenation of dibromide and diiodide precursors and trapped in situ. retro-Diels-Alder reaction of its adduct with N-benzylpyrrole has made the alkene available in high yield and purity. In sharp contrast to its extremely labile hydrocarbon counterpart, the fluoroalkene is very stable yet highly reactive. Its characterization includes its electron affinity, photoelectron spectrum, and the previously reported structure determination by electron diffraction.

Methyl 1-benzyl-5-methyl-2,4-diphenyl-1H-pyrrole-3-carboxyl-ate.

In the title compound, C26H23NO2, the dihedral angles between the pyrrole ring and the two phenyl rings are 58.1 (6) and 71.5 (5)°. The mean planes of the 5-methyl-benzene ring and the carboxyl group are twisted by 89.5 (3) and 22.1 (9)°, respectively, from the pyrrole ring. In the crystal, weak C-H⋯O inter-actions lead to supra-molecular layers in the ab plane.

(Z)-1-Di-phenyl-methyl-4-(3-phenyl-prop-2-en-yl)piperazine.

In the title compound, C26H28N2, the piperazine group adopts a chair conformation with the exocyclic N-C bonds in equatorial orientations. The dihedral angle between the geminal benzene rings is 80.46 (12)° and the C=C-C-N torsion angle is 145.9 (2)°. In the crystal, weak C-H⋯π inter-actions link the mol-ecules into [100] chains.

(E)-2-{[4-(Di-methyl-amino)-benzyl-idene]amino}-5-nitro-phenol.

The title Schiff base compound, C15H15N3O3, crystallizes with two mol-ecules (A and B) in the asymmetric unit. Each mol-ecule adopts an E conformation around the C= N imine bond. The two mol-ecules have minor differences in their conformations. In mol-ecule A, the dihedral angle between the nitro group and its benzene ring is 2.1 (2)° and that between the two benzene rings is 0.88 (7)°, while the corresponding angles for mol-ecule B are 5.7 (1) and 2.45 (6)°, respectively. In each mol-ecule, there is an intra-molecular O-H⋯N hydrogen bond. In the crystal, inversion-related mol-ecules are linked via O-H⋯O hydrogen bonds forming A-A and B-B dimers. These dimers are linked via C-H⋯O hydrogen bonds involving the nitro O atoms, forming A-A-A and B-B-B slabs that lie parallel to one another and to (010).

1-[Bis(4-fluoro-phen-yl)meth-yl]-4-[(2Z)-3-phenyl-prop-2-en-1-yl]piperazine-1,4-diium dichloride hemihydrate.

The asymmetric unit of the title monohydrated salt, 2C26H28F2N2 (2+)·4Cl(-.)H2O, consists of a 1-[bis-(4-fluoro-phen-yl)meth-yl]-4-[(2Z)-3-phenyl-prop-2-en-1-yl]piperazine-1,4-diium cation with a diprotonated piperizine ring in close proximity to two chloride anions and a single water mol-ecule that lies on a twofold rotation axis. In the cation, the piperazine ring adopts a slightly distorted chair conformation. The dihedral angles between the phenyl ring and the 4-fluoro-phenyl rings are 89.3 (9) and 35.0 (5)°. The two fluoro-phenyl rings are inclined at 65.0 (5)° to one another. In the crystal, N-H⋯Cl hydrogen bonds and weak C-H⋯Cl inter-molecular inter-actions link the mol-ecules into chains along [010]. In addition, weak C-H⋯O inter-actions between the piperizine and prop-2-en-1-yl groups with the water mol-ecule, along with weak C-H⋯Cl inter-actions between the prop-2en-1-yl and methyl groups with the chloride ions, weak C-H⋯F inter-actions between the two fluoro-phenyl groups and weak O-H⋯Cl inter-actions between the water mol-ecule and chloride ions form a three-dimensional supra-molecular network.

N-Ethyl-2-[1-(2-hy-droxy-naphthalen-1-yl)ethyl-idene]hydrazinecarbo-thio-amide.

In the title compound, C15H17N3OS, the dihedral angle between the mean planes of the 2-hy-droxy-napthyl ring system and the hydrazinecarbo-thio-amide group is 73.7 (3)°. In the crystal, weak O-H⋯S and C-H⋯O inter-actions and π-π stacking inter-actions involving one of the hy-droxy-napthyl rings with a centroid-centroid distance of 3.6648 (14) Šare observed, forming infinite chains along [010]. In addition, N-H⋯S inter-actions occur.

N-Ethyl-2-[1-(2-hy-droxy-4-methyl-phen-yl)ethyl-idene]hydrazinecarbo-thio-amide.

The title compound, C12H17N3OS, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. The dihedral angle between the mean planes of the benzene ring and the hydrazinecarbo-thio-amide group are 6.9 (4) and 37.2 (5)° in mol-ecules A and B, respectively. An intra-molecular O-H⋯N hydrogen bond is observed in each mol-ecule. This serves to maintain an approximately planar conformation for mol-ecule A, but leaves a significant twist between these two groups in mol-ecule B. In the crystal, a weak N-H⋯S inter-action is observed, forming inversion dimers among the B mol-ecules and resulting in an R 2 (2)(8) motif. These dimers are further inter-connected by weak N-H⋯O and C-H⋯O inter-molecular inter-actions, forming chains along [011].

(E)-2-{[(Furan-2-ylmeth-yl)imino]-meth-yl}-4-nitro-phenol.

In the title compound, C12H10N2O4, the furan-2-ylmethyl group is disordered over two sets of sites, with refined occupancies of 0.858 (3) and 0.143 (3). In the major component of disorder, the dihedral angle between the furan and benzene rings is 63.1 (2)° and for the minor component this value is 67.9 (6)°. The planes of the nitro group and the attached benzene ring form a dihedral angle of 4.34 (17)°. In the crystal, inversion-related mol-ecules are linked by two pairs of weak C-H⋯O inter-actions, one involving the nitro group and the other involving the O-H group as an acceptor. As a result of these associations, ribbons are formed along [120]. A strong intra-molecular O-H⋯N hydrogen bond is observed.

(4-Methyl-piperazin-1-yl)(2,3,4-tri-meth-oxy-benzyl-idene)amine.

In the title compound, C15H23N3O3, the piperazine ring is in a slightly distorted chair conformation and is twisted from the mean plane of the benzene ring making a dihedral angle of 14.94 (6)°. The 4-meth-oxy substituent is almost co-planar with the benzene ring [C-C-O-C torsion angle = 5.4 (1)°], while the meth-oxy groups at positions 2 and 3 [C-C-O-C torsion angles of 122.6 (4) and -66.1 (4)°, respectively] are twisted away from the mean plane of the benzene ring in anti-clinical and synclinical conformations, respectively. No classical hydrogen bonds or any weak inter-molecular inter-actions are observed in the crystal structure.

2,5-Di-methyl-phenyl quinoline-2-carboxy-l-ate.

In the title compound, C18H15NO2, the dihedral angle between the mean planes of the quinoline ring system and the phenyl ring is 78.8 (1)°. The mean plane of the carboxyl-ate group is twisted from the mean planes of the quinoline ring system and phenyl ring by 1.5 (9) and 77.6 (4)°, respectively. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, generating C(8) chains along [001]. Weak π-π stacking inter-actions are also observed [centroid-centroid separation = 3.6238 (12) Å].

4-[(4-Acetyl-phen-yl)amino]-2-methyl-idene-4-oxo-butanoic acid.

In the title compound, C13H13NO4, the N-C(=O) bond length of 1.354 (2) Šis indicative of amide-type resonance. The dihedral angle between the mean planes of the benzene ring and oxo-amine group is 36.4 (3)°, while the mean plane of the 2-methyl-idene group is inclined by 84.2 (01)° from that of the oxo-amine group. In the crystal, classical O-H⋯O hydrogen bonds formed by the carb-oxy-lic acid groups and weak N-H⋯O weak inter-actions formed by the amide groups and supported by weak C-H⋯O inter-actions between the 2-methyl-idene, phenyl and acetyl groups with the carb-oxy-lic acid, oxo-amine and acetyl O atoms, together link the mol-ecules into dimeric chains along [010]. The O-H⋯O hydrogen bonds form R 2 (2)(8) graph-set motifs.

1-{3-(4-Chloro-phen-yl)-5-[4-(propan-2-yl)phen-yl]-4,5-di-hydro-1H-pyrazol-1-yl}butan-1-one.

In the title compound, C22H25ClN2O, the pyrazole ring exhibits an envelope conformation with the methine C atom as the flap. The benzene rings are twisted by 3.3 (5) and 84.6 (5)° from the pyrazole mean plane, and are inclined to each other by 81.4 (4)°. In the crystal, pairs of weak C-H⋯O hydrogen bonds form centrosymmetric dimers with an R 2 (2)(16) graph-set motif. C-H⋯π inter-actions link the dimers into columns propagating in [100].

1-{3-(4-Chloro-phen-yl)-5-[4-(propan-2-yl)phen-yl]-4,5-di-hydro-1H-pyrazol-1-yl}propan-1-one.

In the title compound, C21H23ClN2O, the dihedral angle between the benzene rings is 83.2 (6)°, while the mean plane of the pyrazole ring [r.m.s. deviation = 0.043 (1) Å] makes dihedral angles of 3.4 (3) and 86.2 (1)° with the benzene rings. In the crystal, a pair of weak C-H⋯O inter-actions between the benzene ring and the propan-1-one group link the mol-ecules into an inversion dimer with an R 2 (2)(16) graph-set motif. In addition, a weak π-π stacking inter-action [centroid-centroid distance = 3.959 (4) Å] connects the dimers into a tape running along [201].

4-[(4-Bromo-phenyl)amino]-2-methyl-idene-4-oxo-butanoic acid.

In the title compound, C11H10BrNO3, two independent mol-ecules (A and B) crystallize in the asymmetric unit. The dihedral angles between the mean planes of the 4-bromo-phenyl ring and amide group are 24.8 (7) in mol-ecule A and 77.1 (6)° in mol-ecule B. The mean plane of the methyl-idene group is further inclined by 75.6 (4) in mol-ecule A and 72.5 (6)° in mol-ecule B from that of the amide group. In the crystal, N-H⋯O hydrogen bonds formed by amide groups and O-H⋯O hydrogen bonds formed by carb-oxy-lic acid groups are observed and supported additionally by weak C-H⋯O inter-actions between the methyl-idene and amide groups. Together, these link the mol-ecules into chains of dimers along [110] and form R 2 (2)(8) graph-set motifs.