Synthesis of C3-Symmetric star-shaped molecules containing 1,3-azoles via hetero-aryl Heck coupling

We have demonstrated a useful synthetic strategy to assemble star-shaped C₃-symmetric molecules containing 1,3-azole moieties at the periphery. To generate these C₃-symmetric heterocycles, we have employed the Pd/Cu-based coupling reactions. To this end, we have used benzoxazole, benzothiazole, and benzimidazole as coupling partners to generate the corresponding hetero-aryl Heck coupling products.     

Synthesis of functionalized cage propellanes and D3-Trishomocubanes via the ring-closing metathesis and acid-promoted rearrangement

Several functionalized cage propellanes and D₃-trishomocubanes containing spiro linkage have been reported starting with commercially available materials such as 1,4-hydroquinone and dicyclopentadiene. In this regard, Claisen rearrangement, Diels–Alder reaction (DA), ring-closing metathesis (RCM) and acid-promoted rearrangement have been used as key steps. The strategies described here, opens up new opportunities to assemble intricate cage systems that are difficult to construct by conventional methods. Carbocation intermediates generated during the rearrangement process play a prominent role in designing unusual cage systems. One of the rearranged cage compound's structure was unambiguously established by single crystal X-ray diffraction studies.     

Synthesis,characterization, biological screening and molecular docking studies of 2-aminonicotinaldehyde (ANA) and its metal complexes

The biological and optical importance of the o-aminoaldehyde family of ligands inspired us to evaluate the coordination properties and biological activities of 2-aminonicotinaldehyde (ANA). Here, we report the synthesis, characterization, biological screening and molecular docking studies of ANA and its metal complexes of Ni(II), Pd(II), Co(II) and Cu(II) using various analytical and spectroscopic techniques. The single crystal X-ray diffraction studies of ANA explain the solid-state assembly and an interesting supramolecular herring bone stacking pattern by classical N–H···O/N intra/inter molecular and non-classical C–H···O/N intermolecular H-bonding. ANA and its metal complexes were screened for in vitro anticancer, antimicrobial and anti-oxidant activities. Anticancer activity was tested against HeLa, MCF-7 and HEK293 human cancer cell lines. The [Ni(ANA)₂Cl₂] complex showed good activity against HeLa and MCF-7, the [Pd(ANA)₂Cl₂] and [Cu(ANA)₂Cl₂] complexes against HeLa, and the [Co(ANA)₂Cl₂] complex against MCF-7. In antimicrobial screening, the [Co(ANA)₂Cl₂] and [Cu(ANA)₂Cl₂] complexes were proved to be potent antibacterial and antifungal agents. The anti-oxidant activity of these complexes was investigated through DPPH radical assay, and it was found that all the complexes have good radical scavenging capability. Molecular docking studies were also carried for all the metal complexes against EGFR as a target protein by using Autodock, and the results strongly correlated with the anticancer activity.     

Application of Claisen Rearrangement and Olefin Metathesis in Organic Synthesis

Several new synthetic methods to diverse polycycles and heterocycles on the basis of [3,3]‐sigmatropic rearrangement and ring‐closing metathesis as key steps are summarized. In this regard, Claisen, aza‐Claisen, and Overman rearrangements are used in combination with other popular reactions such as ring‐closing metathesis, Suzuki coupling, Diels–Alder reaction, and retro‐Diels–Alder reaction. To this end, we prepared polycycles (e.g., cyclophanes, cage molecules), heterocycles (e.g., oxepins, azapins), carbocycles, and spirocycles with the use of the above protocol.     

Synthesis of liquid crystalline materials based on 1,3,5-triphenylbenzene and 2,4,6-triphenyl-1,3,5-s-triazine

C₃-symmetric alkyloxy/aryloxy polyether dendrimers have been synthesized from 1,3,5-triphenylbenzene and 2,4,6-triphenyl-1,3,5-s-triazine and their liquid crystalline properties have been studied. C₃-symmetric derivatives with n-hexyl and n-dodecyl chains at the periphery show mesophase properties when they are complexed with trinitrofluorenone at different temperatures.     

Nano Gd2O3 catalyzed synthesis and anti-oxidant activity of new α-aminophosphonates

A one pot three-component nano Gd₂O₃ catalyzed neat reaction of 2-morpholinoethanamine and dimethylphosphite with various salicylaldehydes under microwave irradiation afforded a series of new α-aminophosphonates in high yields. The synthesized compounds were characterized by FT-IR, (¹H, ¹³C, ³¹P)-NMR, and mass spectral methods. The antioxidant activity of these compounds was evaluated against DPPH, NO, and H₂O₂ methods and found that the compound Dimethyl (2-hydroxy-5-nitrophenyl) (2-morpholinoethylamino) methylphosphonate (4h) has higher antioxidant activity than the corresponding standards.     

Synthesis,Characterization, DNA Binding Studies,Photocleavage, Cytotoxicity and Docking Studies of Ruthenium(II) Light Switch Complexes

A new ligand 3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2yl)phenylboronic acid and its (IPPBA) three ruthenium(II) complexes [Ru(phen)₂(IPPBA)](ClO₄)₂ (1), [Ru(bpy)₂(IPPBA)](ClO₄)₂ (2) and [Ru(dmb)₂(IPPBA)](ClO₄)₂ (3) have been synthesized and characterized by elemental analysis, UV/VIS, IR, ¹H-NMR,¹³C-NMR and mass spectra. The binding behaviors of the three complexes to calf thymus DNA were investigated by absorption spectra, emission spectroscopy, viscosity measurements, thermal denaturation and photoactivated cleavage. The DNA-binding constants for complexes 1, 2 and 3 have been determined to be 7.9?×?10⁵ M^?1, 6.7?×?10⁵ M^?1 and 2.9?×?10⁵ M^?1. The results suggest that these complexes bound to double-stranded DNA in an intercalation mode. Upon irradiation at 365 nm, three ruthenium complexes were found to promote the cleavage of plasmid pBR322 DNA from super coiled form ? to nicked form ??. Further in the presence of Co²⁺, the emission of DNA–Ru(ΙΙ) complexes can be quenched. And when EDTA was added, the emission was recovered. The experimental results show that all three complexes exhibited the “on–off–on” properties of molecular “light switch”. The highest Cytotoxicity potential of the complex1 was observed on the Human alveolar adenocarcinoma (A549) cell line. Good agreement was generally found between the spectroscopic techniques and molecular docked model which provides further evidence of groove binding.     

Study of DNA Light Switch Ru(II) Complexes : Synthesis,Characterization, Photocleavage and Antimicrobial Activity

The three Ru(II) complexes of [Ru(phen)₂dppca]²⁺ (1) [Ru(bpy)₂dppca]²⁺ (2) and [Ru(dmb)₂dppca]²⁺ (3) (where phen = 1,10 phenanthroline, bpy = 2,2-bipyridine, dmb = 2 ,2-dimethyl 2′,2′-bipyridine and polypyridyl ligand containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light switches, as evidenced by UV-visible and luminescence titrations with Co²⁺ and EDTA, steady-state emission quenching by [Fe(CN)₆]⁴⁻ and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1 > 2 > 3. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA.     

Strategies and tactics in olefin metathesis

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