Makuteswaran Sridharan

Novel 13H-indolo[3,2-c]acridines and their methyl derivatives

7-Phenyl-13H-indolo[3,2-c]acridines (2a–e) have been prepared from 2,3,4,9-tetrahydro-1H-carbazol-1-ones (1a–e) via the intermediate 5,6-dihydro-derivatives (3a–e), and 13H-indolo[3,2-c]acridines (8a–e) from the 1-(N-phenylamino)carbazoles (7a–e). Methylations of 2 and 8 have been carried out, and UV spectral studies on the title compounds and the methylated products are presented, along with plausible mechanisms for the formation of the final compounds.

Phenolic compounds in drumstick peel for the evaluation of antibacterial, hemolytic and photocatalytic activities

Most of the wastes emitted from the food processing industries are not utilized for any further purpose. The economic value of the food waste is very less when compared to the collection or reuse or discard. To increase the economic value we have to design the food waste as useful product or applicable in most of the current field. Nothing is waste in this world with this concept we have investigated the phytochemical analysis of drumstick peel (Moringa oleifera). The result supports the presence of phenols, alkaloids, flavanoids, glycosides and tannins. Since various functional groups containing molecules are present in the extract; it has been further subjected to antibacterial and hemolytic activities. To analysis the antibacterial studies we have employed human pathogenic Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterium. The result of antibacterial activity clearly shows that it possesses significant activity on both bacterial cultures. The hemolytic activity was performed on red blood cells (RBCs). From this result we observed that drumstick peel extract has been considered as non-toxic on RBCs. Malachite green was selected to perform photocatalytic activity. The results stated that the drumstick peel extract possessed good behaviour towards photocatalytic investigation. The malachite green was degraded upto 99.7% using drumstick peel extract.

Syntheses of pyrazolo-, isoxazolo-, pyrido-and pyrimido-carbazoles from 2-(3',4'-dimethoxybenzylidene)-2,3,4,9-tetrahydrocarbazol-1-ones

Mixed aldol condensation of 2,3,4,9-tetrahydrocarbazol-1-ones with 3,4-dimethoxybenzaldehyde (veratraldehyde) yielded 2-(3′,4′-dimethoxybenzylidene)-2,3,4,9-tetrahydrocarbazol-1-ones. These enones on reaction with hydrazine hydrate, hydroxylamine hydrochloride, malononitrile and guanidinium nitrate under different conditions yielded the corresponding pyrazolo[3,4-a]-, isoxazolo[3,4-a]-, pyrido[2,3-a]-, and pyrimido[4,5-a]-carbazoles respectively. The molecular and crystal structure of 2-(3′,4′-dimethoxybenzylidene)-2,3,4,9-tetrahydro-1H-carbazol-1-one resolved by single crystal X-ray diffraction is discussed.

Syntheses of Substituted Furo- and Pyrano-(2,3-a)carbazoles from 2-Cinnamoyl-1-hydroxycarbazoles

Reaction of 2-cinnamoyl-1-hydroxycarbazoles 2a - d, with phenacyl bromide, mercuric acetate and H2O2/NaOH under different reaction conditions yielded 2-benzoyl-3-styryl-furo[2,3-a]carbazoles 3a-d, 2-benzylidene-furo[2,3-a]carbazol-3(10H)-ones 4a - d and 3-hydroxy-2-phenylpyrano- [2,3-a]carbazol-4(11H)-ones 5a - d, respectively.

7,8,9,10-Tetra-hydro-2-methyl-cyclo-hepta-[b]indol-6(5H)-one.

The title compound, C14H15NO, was synthesized from 2-hydroxymethylenecycloheptanone via a Japp–Klingemann acid-catalyzed cyclization. The seven-membered ring exhibits a slightly distorted envelope conformation. N—H⋯O hydrogen bonds form a centrosymmetric dimer; C—H⋯O hydrogen bonds and π–π stacking interactions (the centers of the atoms involved in the stacking interaction are separated by 3.504 Å) give rise to another type of centrosymmetric dimer. In combination, these interactions create a stair-like chain of molecules that interacts only loosely with neighboring chains via van der Waals interactions and weak C—H⋯π contacts.

2,2,10-Trimethyl-2,3-dihydro­pyrano[2,3-a]carbazol-4(11H)-one

The title compound, C18H17NO2, was prepared from 1-hydroxy-7-methylcarbazole and 3,3-dimethylacrylic acid with trifluoroacetic acid as the cyclization catalyst. The molecules contain an essentially planar 6-methylindole unit. The second aromatic ring is significantly bent away from the plane of this unit, with maximum deviations of 0.171 (1) and 0.185 (1) Å for two of the C atoms. In the crystal structure, there are neither N—H⋯O hydrogen bonds nor π–π stacking between the aromatic sections of neighboring molecules. There is only one weak C—H⋯O hydrogen bond and a number of weak C—H⋯π interactions.

Synthetic utility of 2-furylmethylene-2,3,4,9-tetrahydrocarbazol-1-ones: syntheses of pyrazolo, isoxazolo, pyrido and pyrimido annelated carbazoles

2-Furylmethylene-2,3,4,9-tetrahydrocarbazol-1-ones were obtained from the mixed aldol condensation of 2,3,4,9-tetrahydrocarbazole-1-ones and furan-2-carbaldehyde (furfural). The corresponding enones were utilised as the synthons to prepare various heteroannulated pyrazolo[3,4-a]-, isoxazolo[3,4-a]-, pyrido[2,3-a]-, and pyrimido[4,5-a] carbazoles under different conditions using various reagents. Single crystal X-ray diffraction studies of 2-furylmeth-ylene-6-methyl-2,3,4,9-tetrahydrocarbazol-1-one are discussed.

4,8-Dimethyl­pyrano[2,3-a]carbazol-2(11H)-one

The molecule of the title compound, C17H13NO2, is nearly planar, the r.m.s. deviation for all non-H atoms excluding the two methyl C atoms being 0.089 Å. Intermolecular N—H⋯O and C—H⋯O hydrogen bonds are found in the crystal structure. C—H⋯π interactions are also found. The H atoms of the methyl group attached to the benzene ring are disordered equally over two positions.

7,8,9,10-Tetra­hydro­cyclo­hepta­[b]indol-6(5H)-one

In the title molecule, C13H13NO, the dihedral angle between the benzene and pyrrole rings is 1.05 (5)°. The cycloheptene ring adopts a slightly distorted boat conformation. In the crystal structure, intermolecular N—H⋯O hydrogen bonds form centrosymmetric dimers. A C—H⋯π interaction, involving the benzene ring, is also found in the structure.

Crystal structure of (E)-2-(furan-2-yl­methyl­idene)-2,3,4,9-tetra­hydro-1H-carbazol-1-one

The title compound crystallized with two conformationally very similar independent molecules (A and B) in the asymmetric unit. In the crystal, the individual molecules are linked by pairs of N—H⋯O hydrogen bonds, forming A–A and B–B inversion dimers, with (10) rings.