Satbir Mor

Synthesis and antimicrobial activities of some isoxazolyl thiazolyl pyrazoles

A series of isoxazolyl thiazolyl pyrazoles 5a–d was synthesized by multi-step process, starting from 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (dehydroacetic acid, DHAA) 1. DHAA 1 was easily converted to thiosemicarbazone 2 which on reaction with α-bromoketones yielded thiazolyl hydrazones 3. Refluxing 3 in ethanol-acetic acid furnished 1-(5-hydroxy-3-methyl-1-substituted pyrazol-4-yl)-1,3-butanediones 4. Finally, the title compounds 5a–d were synthesized from 4 on treatment with hydroxylamine. The in vitro antimicrobial activity of compounds 3a–d, 4a–d and 5a–d were tested. Most of the synthesized compounds exhibited significant antibacterial and antifungal activities.

On the mechanism for the phototransformation of 3-alkoxy-2-(2′-furyl)-4-oxo-4H-1-benzopyrans

Photoirradiation of 3-alkoxy-6-chloro-2-(2′-furyl)-4-oxo-4H-1-benzopyrans 3 led to the formation of methyl 8-chloro-10-oxo-2-phenyl-2,3,4,10-tetrahydropyrano[3,2-b][1]benzopyran-3-ylacetate 4. The reaction proceeds through the formation of 8-chloro-4-phenyl-3a,4,6,11b-tetrahydrofuro-[2′,3′:4,5]pyrano[3,2-b]benzopyran-6-one 5a, which subsequently undergoes a ring contraction–ring expansion mechanism to give the cyclopropanecarbaldehyde 8 followed by its rearrangement to ketene 10via the carbene 9 to furnish ester 4. The various intermediates have been isolated and identified, and their stereochemistry was established from their 1H NMR spectra.

Synthesis, characterization, antimicrobial activities and QSAR studies of some 10a-phenylbenzo[b]indeno[1,2-e][1,4]thiazin-11(10aH)-ones.

A series of 10a-phenylbenzo[b]indeno[1,2-e][1,4]thiazin-11(10aH)-ones (3) has been synthesized and tested for their antimicrobial activity. The antimicrobial evaluation data indicated that compounds, 3b, 3d, 3k and 3m exhibited very promising antibacterial activity and the compounds 3b and 3k exhibited notable activity, almost comparable to penicillin for Staphylococcus aureus and Bacillus subtilis respectively. The derivatives 3g and 3l exhibited high antifungal activity. Moreover, antibacterial activities were more prolific than antifungal activity. The QSAR studies indicated the importance of topological parameters, Kiers second order molecular index (κα(2)) and molecular connectivity index (χ) in describing the antibacterial activity and electronic parameters, the energy of highest occupied molecular orbital (HOMO) and the dipole moment (μ) in describing the antifungal activity.

Synthesis, characterization, biological evaluation and QSAR studies of 11-p-substituted phenyl-12-phenyl-11a,12-dihydro-11H-indeno[2,1-c][1,5]benzothiazepines as potential antimicrobial agents.

A novel series of 11-p-substituted phenyl-12-phenyl-11a,12-dihydro-11H-indeno[2,1-c][1,5]benzothiazepines (3) has been synthesized and screened for their antimicrobial activity against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and fungi (Aspergillus fumigates and Candida albicans). The antimicrobial evaluation data indicated that the compounds, 3d, 3g, 3h, 3k-3p exhibited very promising antibacterial activity and the derivatives 3k, 3l, 3o and 3p exhibited high antifungal activity. The QSAR studies carried out to find out the correlation between the antimicrobial activity and physicochemical properties of synthesized benzothiazepines (3) indicated the predominance of electronic parameters in describing their antimicrobial activity.

In(OTf)3 catalysed an expeditious synthesis of β-carboline–imidazo[1,2-a]pyridine and imidazo[1,2-a]pyrazine conjugates

β-Carboline containing alkaloids are ubiquitously present in Nature, while imidazo[1,2-a]pyridine nucleus is incorporated in various synthetic commercial drugs and biologically previliged moieties. On this basis, new β-carboline–imidazoazine conjugates were designed and a small library of compounds integrating both the pharmacophores was constructed with 4-points of diversity by using the In(OTf)3 assisted Groebke–Blackburn–Bienayme multicomponent strategy. The methodology was found to be simple and convenient for the efficient syntheses of β-carboline–imidazo[1,2-a]azine conjugates. The present synthetic protocol provides several advantages like operational simplicity, appreciable atom economy, short reaction time and easy purification procedure.

In(OTf)3 assisted synthesis of β-carboline C-3 tethered imidazo[1,2-a]azine derivatives

Synthesis of β-carboline based natural products and synthetic derivatives is one of the frontier areas of research owing to their medicinal properties. It is envisaged that 3-formyl-9H-β-carboline is a potential precursor and offers new vistas for the construction of a variety of heterocyclic architectures at the C-3 position of the β-carboline skeleton. In this context, an efficient protocol has been developed for the synthesis of β-carboline C-3 tethered imidazo[1,2-a]pyridine, imidazo[1,2-a]pyrimidine, and imidazo[1,2-a]pyrazine derivatives via exploration of the Groebke–Blackburn–Bienayme (GBB) reaction. The present protocol offers several advantages like operational simplicity, high atom economy, appreciable structural diversity and easy purification procedure.

Efficient and convenient synthesis, characterization, and antimicrobial evaluation of some new tetracyclic 1,4-benzothiazines

ABSTRACT In the present study, 20 new tetracyclic 1,4-benzothiazines (4a–4 t) were conveniently synthesized in good yields and characterized by different spectral and physical techniques. The in vitro antimicrobial evaluation of the synthesized benzothiazine derivatives was performed by serial dilution against two Gram-positive bacteria [Bacillus subtilis (MTCC 441) and Staphylococcus epidermidis (MTCC 6880)], two Gram-negative bacteria [Escherichia coli (MTCC 1652) and Pseudomonas aeruginosa (MTCC 424)], and two fungal strains [Candida albicans (MTCC 227) and Aspergillus niger (MTCC 8189)]. The derivatives 4 l and 4 t were found to be more potent than standard drug, i.e., fluconazole, against A. niger and C. albicans, respectively. GRAPHICAL ABSTRACT

Efficient synthesis and antimicrobial evaluation of 2-((1-substituted-1H-1,2,3-triazol-4-yl)-1-naphthaldehydes and their oxime derivatives

A series of 2-((1-substituted-1H-1,2,3-triazol-4-yl)-1-naphthaldehydes was prepared by the propargylation of 2-hydroxynaphthaldehyde followed by Copper(I)-catalyzed azide-alkyne cycloaddition with various organic azides. 2-((1-substituted-1H-1,2,3-triazol-4-yl)-1-naphthaldehyde analogues were transformed to corresponding oxime derivatives upon grinding with hydroxylamine hydrochloride under solvent free conditions. All the synthesized compounds were characterized by various analytical and spectral techniques and screened in vitro for antimicrobial activity. The activity data revealed that most of the compounds exhibited good to significant activities. Compounds 4c and 5c exhibited very good and broad spectrum activity towards all the tested bacterial strains. Further, to understand the binding interactions, 4c and 5c were docked into the active sites of E. coli topoisomerase II DNA gyrase.

Convenient synthesis, anticancer evaluation and QSAR studies of some thiazole tethered indenopyrazoles

A convenient one-pot synthesis of twelve new thiazole tethered indeno[1,2-c]pyrazol-4-ones (3a–3l) was carried out by three-component reaction between 1,3-diketones, thiosemicarbazide and α-bromoketones in high yields. Wolff-Kishner reduction of indeno[1,2-c]pyrazol-4-ones (3a–3l) led to the formation of corresponding indeno[1,2-c]pyrazoles (4a–4l) in moderate-to-good yields. The structures of all the synthesized indenopyrazoles were elucidated by IR, 1H NMR, 13C NMR and mass spectral techniques. In vitro cytotoxicity of thiazole tethered indenopyrazoles (3a–3l & 4a–4l) was evaluated against different human cancer cell lines, viz. human renal carcinoma (A498), human colorectal adenocarcinoma (HT29), human breast adenocarcinoma (MCF-7), human hepatocellular carcinoma (HepG2) and normal cell line, i.e., normal rat kidney epithelial (NRK). Among all the tested derivatives, 4a, 4d and 4h exhibited better activity against HT29 cancer cell line. The statistically significant QSAR models were developed for all the cancer cell lines using multiple linear regression analysis to understand the observed activity trend on structural basis.Graphical Abstract

QSAR Studies and Design of Some Tetracyclic 1,4-Benzothiazines as Antimicrobial Agents.

A quantitative structure-activity relationship (QSAR) analysis has been performed on a series of 20 tetracyclic 1,4-benzothiazines (1a-1t) with antimicrobial activity to explain the observed biological activity trend on structural basis. Multiple linear regression (MLR) method was employed to establish statistically significant QSAR models. The developed models are robust, predictive and free from chance correlation with good fitting ability and sufficient generalizability. These studies revealed the dominance of WHIM parameters in describing antimicrobial activity of the title compounds. Further, design of some more active compounds is presented.