Carbazole Ring System Research Articles

Crystal structure of 9-butyl-6-[2-(pyridin-4-yl)ethen-yl]carbazol-3-amine.

The asymmetric unit of the title compound, C23H23N3, consists of two mol­ecules, A and B, with different conformations. In mol­ecule A, the dihedral angle between the carbazole ring system (r.m.s. deviation = 0.028 Å) and the pyridine ring is 20.28 (9)° and the N—C—C—C torsion angle of the butyl side chain is −63.4 (3)°. The equivalent data for mol­ecule B are 0.065 Å, 48.28 (11)° and 61.0 (3)°, respectively. In the crystal, the components are connected by weak N—H⋯N hydrogen bonds, generating [030] C(14) chains of alternating A and B mol­ecules.

Crystal structure of (E)-N-(3,3-di-phenyl-allyl-idene)-9-ethyl-9H-carbazol-3-amine.

In the title compound, C29H24N2, the C=N bond of the central imine group adopts an E conformation. The dihedral angles between the mean plane of the essentially planar carbazole ring system [r.m.s. deviation = 0.039 (2) Å] and the two phenyl rings of the 3,3-di-phenyl-allyl-idene unit are 75.9 (1) and 64.6 (1)°. In the crystal, mol-ecules are linked by C-H⋯π inter-actions, forming a three-dimensional supra-molecular network.

Crystal structure of 9-butyl-3-(9-butyl-9H-carbazol-3-yl)-9H-carbazole

In the title carbazole derivative, C32H32N2, the mol­ecule resides on a crystallographic twofold axis, which runs through the central C—C bond. The carbazole ring system is almost planar, with a maximum deviation of 0.041 (1) Å for one of the ring-junction C atoms. The crystal packing is stabilized by C—H⋯π inter­actions only, which form a C(7) chain-like arrangement along [110] in the unit cell.

Substituent Effect of Nitro Group on Aromaticity of Carbazole Rings

The molecular geometries of carbazole and its 17 nitro derivatives were optimized at the B3LYP/6-311++G(2d,2p) level of theory. The harmonic oscillator model of aromaticity and nucleus-independent chemical shift descriptors of π-electron delocalization were calculated to estimate the aromaticity of the carbazole five- and six-membered rings. The biggest changes in the value of both descriptors were observed for the pyrrole ring. The nitro group attached to 3 and/or 6 positions of the carbazole ring system exerts only a slight influence on the benzene ring aromaticity.

Crystal structure of 2-(2,4-di-chloro-phen-yl)-4-hydroxy-9-phenyl-sulfonyl-9H-carbazole-3-carbaldehyde.

In the title compound, C25H15Cl2NO4S, the di-chloro-phenyl ring is twisted by 68.69 (11)° from the mean plane of the carbazole ring system [r.m.s. deviation = 0.084 (2)°]. The hy-droxy group is involved in an intra-molecular O-H⋯O hydrogen bond, which generates an S(6) graph-set motif. In the crystal, pairs of C-H⋯Cl hydrogen bonds link mol-ecules into inversion dimers with an R (2) 2(26) motif. Weak C-H⋯O inter-actions further link these dimers into ribbons propagating in [100].

(E)-3-(9-Hexyl-9H-carbazol-3-yl)acrylic acid.

In the title compound, C21H23NO2, the hexyl group adopts an extended conformation, the six C atoms are nearly coplanar [maximum deviation = 0.082 (3) Å] and their mean plane is approximately perpendicular to the carbazole ring system, with a dihedral angle of 78.91 (15)°. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds, forming inversion dimers; π–π stacking between carbazole ring systems of adjacent dimers further links the dimers into supra­molecular chains propagating along the b-axis direction [centroid-to-centroid distances = 3.868 (2) and 3.929 (2) Å].

2-(4,5-Dimeth-oxy-2-nitro-phen-yl)-4-meth-oxy-9-phenyl-sulfonyl-9H-carbazole-3-carbaldehyde.

In the title compound, C28H22N2O8S, the carbazole ring system is roughly planar, with a maximum deviation of 0.084 (3) Å for the C atom connected to the 4,5-dimeth­oxy-2-nitro­phenyl ring. The dihedral angle between the carbazole system and the dimeth­oxy-substituted nitro­phenyl ring is 57.05 (10)°. The aldehyde C atom deviates by 0.164 (5) Å from its attached carbazole ring system. The mol­ecular structure is stabilized by C—H⋯O inter­actions which generate two S(6) and one S(7) ring motif. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming R 3 3(15) ring motifs, which are further crosslinked by R 3 2(19) ring motifs, resulting in (002) layers. The crystal packing also features C—H⋯π inter­actions.

N-[2-(9H-Carbazol-9-yl)ethyl]-4-(methylsulfonyl)aniline

In the title mol­ecule, C21H20N2O2S, the dihedral angle between the mean plane of the carbazole ring system [maximum deviation = 0.021 (4) Å] and the benzene ring is 80.15 (6)°. In the crystal, mol­ecules are linked by N—H⋯O and weak C—H⋯O hydrogen bonds into a C(8) chain along [001].

2-(4-Fluoro-2-nitro-phen-yl)-4-hy-droxy-9-phenyl-sulfonyl-9H-carbazole-3-carbaldehyde.

In the title compound, C25H15FN2O6S, the carbazole ring system is essentially planar, with a maximum deviation of 0.1534 (16) Å for the C atom connected to the 4-fluoro-2-nitro­phenyl ring. It is almost orthogonal to the phenyl­sulfonyl and nitro­phenyl rings, making dihedral angles of 88.45 (8) and 79.26 (7)°, respectively. The mol­ecular structure is stabilized by O—H⋯O and C—H⋯O hydrogen bonds, which generate three S(6) ring motifs. In the crystal, mol­ecules are linked by two C—H⋯O hydrogen bonds, which generate C(6) and C(9) chains running in the [100] and [010] directions, respectively, so forming a two-dimensional network lying parallel to (001). There are also supra­molecular R 4 3(28) graph-set ring motifs enclosed within these networks.

2-(4,5-Di-chloro-2-nitro-phen-yl)-4-meth-oxy-3-methyl-9-phenyl-sulfon-yl-9H-carbazole.

In the title compound, C26H18Cl2N2O5S, the carbazole ring system is essentially planar with a maximum deviation of 0.0498 (16) Å for the N atom. The carbazole ring system is almost orthogonal to the phenyl­sulfonyl and di­chloro-substituted nitro­phenyl rings, making dihedral angles of 84.23 (7) and 85.46 (12)°, respectively. The mol­ecular structure features intra­molecular C—H⋯O inter­actions, which generate two S(6) ring motifs. In the crystal, mol­ecules are linked by C—Cl⋯O halogen bonds [3.016 (3) Å, 166.63 (5)°], which generate infinite C(8) chains running parallel to [010].

9-[4-(Azido-meth-yl)phen-yl]-9H-carbazole-3-carbo-nitrile.

In the title compound C20H13N5, the dihedral angle between the carbazole ring system (r.m.s. deviation = 0.027 Å) and the pendant benzene ring is 55.08 (6)°. One of the azide N atoms is disordered over two positions in a 0.65 (2):0.35 (2) ratio. In the crystal, aromatic π–π stacking is observed [minimum centroid–centroid separation = 3.6499 (13) Å] as well as inversion-dimers connected by pairs of weak C—H⋯π inter­actions.

(E)-3-(9-Ethyl-9H-carbazol-3-yl)-1-(2-meth-oxy-phen-yl)prop-2-en-1-one.

In the title mol­ecule, C24H21NO2, the dihedral angle between the carbazole ring system [with a maximum deviation of 0.052 (2) Å] and the benzene ring is 38.6 (1)°. In the crystal, weak bifurcated (C—H)2⋯O hydrogen bonds link the mol­ecules into chains along [100].

3,6-Dichloro-9-(prop-2-yn-1-yl)-9H-carbazole

The tricyclic aromatic ring system of the title compound, C15H9Cl2N, is essentially planar (r.m.s. deviation = 0.002 Å). The two Cl atoms lie slightly out of the plane of the carbazole ring system, with the C—Cl bonds forming angles of 1.23 (8) and 1.14 (8)° with the plane. The acetylene group has a syn orientation with respect to the ring system. In the crystal, no weak hydrogen bonds nor any π–π stacking inter­actions are observed.

2-(4-Chloro-2-nitrophenyl)-9-phenylsulfonyl-9H-carbazole-3-carbaldehyde

In the title compound, C25H15ClN2O6S, the carbazole ring system is essentially planar, with a maximum deviation of 0.152 (3) Å for the C atom to which the 4-chloro-2-nitro­phenyl ring is attached. Its mean plane is almost orthogonal to the phenyl­sulfonyl and nitro­phenyl rings, making dihedral angles of 82.64 (14) and 79.89 (13)°, respectively. The N atom of the nitro group deviates by 0.032 (3) Å from the benzene ring to which it is attached. The mol­ecular structure features intra­molecular O—H⋯O and C—H⋯O hydrogen bonds, which generate three S(6) ring motifs. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, which generate C(6) and C(9) chains running in the [100] and [010] directions, respectively, forming a two-dimensional network lying parallel to (001). There are also R 4 3(28) supra­molecular graph-set ring motifs enclosed within these networks.

Discovery of novel N-substituted carbazoles as neuroprotective agents with potent anti-oxidative activity

Carbazole moiety is an important scaffold with a variety of biological applications, for example, anti-oxidative stress. Our previous synthesized carbazoles were screened for their neuroprotective properties against two individual oxidative stresses. Some of the new carbazole derivatives were observed with modest to good neuroprotective effects on neuronal cells HT22 against cell injury induced by glutamate or homocysteic acid (HCA). Substituents introduced to the carbazole ring system play crucial roles in their biological activities. In particular, a bulky group favors the neuroprotective activity of the compounds. One of the new compounds, 6, showed the best neuroprotective effects, which might result from its anti-oxidative activity with a GSH-independent mechanism. These findings might provide an alternative strategy for the development of novel carbazole derivatives for the treatment of CNS diseases such as Alzheimer's disease.

2-[4-(Carbazol-9-yl)phenyl]-1,3-diethyl-1,3-diphenylguanidine

In the title compound, C35H32N4, the C—N bond lengths in the guanidine part are 1.286 (3), 1.387 (2) and 1.414 (2) Å, indicating double- and single-bond character. The N—C—N angles are 114.48 (17), 118.78 (17) and 126.72 (17)°, showing a deviation of the CN3 plane from an ideal trigonal–planar geometry. The carbazole ring system is almost planar (r.m.s. deviation = 0.002 Å). In the crystal, mol­ecules are connected by weak C—H⋯N hydrogen bonds, generating a zigzag chain along the ac plane. Weak π–π inter­actions [centroid–centroid distance = 3.785 (1) Å] between two phenyl rings of the guanidine moiety are also present.

9H-Carbazole-9-carbothioic dithioperoxyanhydride

The whole mol­ecule of the title compound, C26H16N2S4, is generated by twofold rotational symmetry. The carbazole skeleton is nearly planar [maximum deviation = 0.054 (5) Å]. In the crystal, aromatic π–π stacking is observed between parallel carbazole ring systems of adjacent mol­ecules, the shortest centroid–centroid distances between pyrrole and benzene rings being 3.948 (3) and 3.751 (3) Å.

N-(2,6-Dimeth-oxy-pyridin-3-yl)-9-methyl-9H-carbazole-3-sulfonamide.

In the title compound, C20H19N3O4S, a novel tubulin ligand active against human cancer, the dihedral angle between the pyridine ring and the carbazole ring system is 42.87 (10)°. In the crystal, the mol­ecules are held together by N—H⋯O and C—H⋯O hydrogen bonds into layers, which are assembled into a three-dimensional network via π–π stacking inter­actions between inversion-related pyridine rings, with centroid–centroid distances of 3.5101 (12) Å.

ChemInform Abstract: A New Route to Pyrano[3,2‐a]carbazole Ring Systems and Annulated Derivatives Thereof.

AbstractA successful application of the Claisen rearrangement/isomerization/ring closing enyne metathesis for the preparation of the title skeleton is described.

A New Route to Pyrano[3,2-a]carbazole Ring Systems and Annulated Derivatives Thereof

A new protocol based on sequential applications of Claisen rearrangement, olefin isomerisation, ring-closing diene/ enyne metathesis and Diels–Alder reaction has been developed to access pyrano[3,2-<i>a</i>]carbazole and annulated derivatives thereof.