D. Jagadeesh Prasad

Synthesis and antitumor activity studies of some new fused 1,2,4-triazole derivatives carrying 2,4-dichloro-5-fluorophenyl moiety

A series of 3-(2,4-dichloro-5-fluorophenyl)-6-(substituted phenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines (4) (Fig. 1) have been synthesized by the cyclization of 3-(2,4-dichloro-5-fluorophenyl)-1,2,4-triazol-5-thiol (3) with substituted phenacyl bromides. All the newly synthesized compounds were confirmed by IR, (1)H NMR and mass spectral studies. Among the compounds tested for their antitumor activity three compounds exhibited in vitro antitumor activity with moderate to excellent growth inhibition against a panel of sixty cancer cell lines of leukemia, non-small cell lung cancer, melanoma, ovarian cancer, prostate and breast cancer. The compound 4d showed promising antiproliferative activity with GI(50) values in the range of 1.06-25.4 microM.

Synthesis and antimicrobial activities of some new triazolothiadiazoles bearing 4-methylthiobenzyl moiety

A series of substituted triazolothiadiazoles have been synthesized by condensing 4-amino-3-[4-methylthiobenzyl]-4H-1,2,4-triazole-5-thiol (5) with substituted aryl furoic acids/aromatic acids in the presence of POCl3. The triazole (5) was obtained by the fusion of 4-methylthiophenyl acetic acid with thiocarbohydrazide. The structures of newly synthesized compounds are characterized by elemental analysis, IR, 1H NMR and mass spectroscopic studies and were screened for their antimicrobial activities. The preliminary results revealed that some of the compounds exhibited promising antimicrobial activities.

SYNTHESIS OF SOME NEW 1,2,4-TRIAZOLO[3,4-b]-THIADIAZOLE DERIVATIVES AS POSSIBLE ANTICANCER AGENTS

3-Substituted-4-amino-5-mercapto-1,2,4-triazoles are versatile synthons for constructing various biologically active heterocycles. Their cyclization with carboxylic acids gives fused five-membered derivatives, whereas with α-bromoketones gives a six-membered heterocycle. In this article we report the synthesis of a series of 1,2,4-triazolo[3,4-b]thiadiazoles 5 starting from 4-amino-3-substituted-5-mercapto-1,2,4-triazoles 3 and fluorobenzoic acids 4 using phosphorous oxychloride as cyclizing agent. Fourteen of the newly synthesized compounds were screened for anticancer properties. Four among them showed in vitro anticancer activity.

Synthesis of Some Thiadiazolotriazinone Derivatives as Possible Antimicrobial Agents

A series of 7-substituted-3-t-butyl 4(H)-1,3,4-thiadiazolo(2,3-c)-1,2,4-triazine-4-one (3) have been synthesized by condensing 4-amino-6-t-butyl-3-mercapto-1,2,4-triazin-5(4H)-one (1) with substituted Arylfuroic acids (2) using POCl3 as a cyclizing agent. The newly synthesized compounds are characterized by elemental analysis, IR, 1H NMR, and mass spectral studies. The compounds were screened for their antibacterial and antifungal activities. Some of the compounds showed promising antibacterial and antifungal activity.

Design and Microwave Assisted Synthesis of Coumarin Derivatives as PDE Inhibitors

Coumarins appended to benzimidazole through pyrazole are designed and synthesized using microwave irradiation. These compounds were analyzed for phosphodiesterase (PDE) inhibition indirectly by motility pattern in human spermatozoa. Some of the synthesized compounds, namely, 5d, 5e, 5f, 5g, 5h, and 5k, have exhibited potent inhibitory activity on PDE.

2-Isobutyl-6-(4-meth­oxy­phen­yl)imidazo[2,1-b][1,3,4]thia­diazole

In the title compound, C15H17N3OS, the dihedral angle between the statistically planar imidazo[2,1-b][1,3,4]thiadiazole fused-ring system (r.m.s. deviation = 0.002 Å) and the methyoxbenzene ring is 4.52 (6)°. In the crystal, molecules are arranged into columns and stacked down the a axis. The crystal structure is stabilized by weak C—H⋯π and π–π interactions [centroid–centroid separations = 3.6053 (8) and 3.7088 (7) Å].

3-[4-(Methylsulfanyl)benzyl]-4-{(1E)-[4-(methylsulfanyl)phenyl]methyleneamino}-4,5-dihydro-1H-1,2,4-triazole-5-thione

Geometric parameters of the title compound, C18H18N4S3, are in the usual ranges. The triazole ring makes dihedral angles of 75.00 (5) and 38.51 (7)degrees with the two aromatic rings. The molecules crystallize as centrosymmetric dimers connected by N-H center dot center dot center dot S hydrogen bonds.

Synthesis, Photophysical and Computational Study of Novel Coumarin Based Organic Dyes

A series of novel coumarin pyrazoline moieties combined with tetrazoles, 3‐(1‐phenyl‐4‐(1H‐tetrazol‐5‐yl)‐1H‐pyrazol‐3‐yl)‐2H‐chromen‐2‐one, 6‐chloro‐3‐(1‐phenyl‐4‐(1H‐tetrazol‐5‐yl)‐1H‐pyrazol‐3‐yl)‐2H‐chromen‐2‐one, 6‐bromo‐3‐(1‐phenyl‐4‐(1H‐tetrazol‐5‐yl)‐1H‐pyrazol‐3‐yl)‐2H‐chromen‐2‐one and 6‐bromo‐3‐(1‐(4‐bromophenyl)‐4‐(1H‐tetrazol‐5‐yl)‐1H pyrazol‐3‐yl)‐2H‐chromen‐2‐one7(a‐d), were designed and synthesized. Single crystal X‐ray diffraction and their interactions were studied by Hirshfeld surface analysis. Thermal stabilities and electrochemical properties of these compounds were examined from differential scanning calorimetry (DSC), thermogravimetric (TGA) and cyclic voltammetric (CV) studies. Their spectroscopic properties were analyzed in various alcohols and general solvents by UV–Vis absorption, fluorescence and time‐resolved spectroscopy. In addition, the ground and excited state electronic properties were investigated using density functional theory (DFT). The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and energy band gap (Eg) values have revealed the effect of substitution of halogens. The substitution has equally affected the ground and excited states of 7(a‐d) compounds. The solvatochromism on absorption, fluorescence spectra and fluorescence lifetimes of these compounds was investigated. All these results showed the chromen‐2‐one of pyrazoline tetrazole derivatives could play an important role in photonic and electronic devices.

Methyl 2-[2-(benzyl-oxycarbonyl-amino)-propan-2-yl]-5-hy-droxy-6-meth-oxy-pyrimidine-4-carboxyl-ate.

In the title compound, C18H21N3O6, a pyrimidine derivative, the dihedral angle between the benzene and pyrimidine rings is 52.26 (12)°. The carboxylate unit is twisted with respect to the pyrimidine ring, making a dihedral angle of 12.33 (7)°. In the crystal, molecules are linked by a pair of O—H⋯O hydrogen bonds, forming an inversion dimer. The dimers are stacked into columns along the b axis through weak C—H⋯O interactions.

N'-(4-Chloro-benzyl-idene)-2-[4-(methyl-sulfan-yl)phen-yl]acetohydrazide.

In the title compound, C16H15ClN2OS, the hydrazine group is twisted slightly: the C—N—N—C torsion angle is 175.46 (13)°. The dihedral angle between the two terminal aromatic rings is 87.01 (8)°. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(8) loops. The dimers are further linked by weak C—H⋯π interactions.