Investigations into the synthesis of amine-linked neodisaccharides

Six tail-to-tail amine-linked neodisaccharides were synthesised as potential glycomimetics. Primary-primary linked compounds were synthesised using Mitsunobu chemistry with glucose-6-sulfonamides as nucleophiles and primary carbohydrate alcohols as electrophiles. Primary-secondary linked compounds were synthesised by epoxide ring opening with carbohydrate 6-amines. Deprotection of all neodisaccharides was carried out using dissolving metal reduction.     

New liquid crystals derived from thiophene connected to the 1,2,3-triazole heterocycle

In this work, six new compound derivatives from thiophene were synthesised. The three symmetrical compounds were synthesised containing two heterocyclic 1,2,3-triazole on each side of thiophene, 2,5-disubstituted and the three non-symmetrical compounds were synthesised containing alkyne groups as a spacer in replacing one of these heterocycles. The structural modifications were made by changing the number of alkoxy groups in order to understand the relation between structure and mesomorphic behaviour. Some of the compounds presented liquid crystalline properties, smectic and nematic mesophases. The non-symmetrical compounds allowed for a low emission in the blue region.     

Acetylene-containing highly birefringent rod-type reactive liquid crystals based on 2-methylhydroquinone

New highly birefringent reactive liquid crystal materials based on the 2-methylhydroquinone core were designed and synthesised. Rod-type liquid crystal compounds bearing photo-crosslinkable reactive group of acryloyl, methacryloyl, cinnamoyl, furylacryloyl group were synthesised by introducing acetylene groups via Sonogashira coupling to obtain high birefringence, and lateral groups such as fluoro and methyl to adjust the temperature of the liquid crystal phase. The synthesised compounds were characterised using nuclear magnetic resonance spectroscopy, mass spectrometry and elemental analysis. In addition, their thermal behaviour was investigated using differential scanning calorimetry and polarised optical microscopy. After aligning the synthesised compounds, liquid crystal films were prepared by photo-irradiation. Photo-elastic modulator results showed that the obtained liquid crystal films had high birefringence (Δn) values of 0.32–0.40.     

Synthesis and characterisation of 3-aza-7-phosphabicyclo[3.3.1]nonan-9-ones

Novel 3-aza-7-phosphabicyclo[3.3.1]nonan-9-ones have been synthesised via the Mannich reaction of a phosphorinanone, a primary amine and formaldehyde. The new phosphorus-nitrogen (PN) compounds are rigid and adopt a twin-chair conformation both in solution and the solid states. The coordination properties of the PN compounds were explored and a stable platinum complex was synthesised in which the PN ligand was bonded through both donor atoms.     

A new eco-friendly strategy for the synthesis of novel antimicrobial spiro-oxindole derivatives via supramolecular catalysis

Novel spiro-oxindole derivatives were synthesised by one-pot multicomponent reaction using isatins, urea and 1,3-dicarbonyls. β-Cyclodextrin, an oligosaccharide, catalysed the reaction and can be reused for further reaction after recovery. This developed synthetic route is environmentally benign in which water is used as solvent to produce excellent yields of products. The synthesised compounds were evaluated for their antimicrobial activities against two bacteria and two fungi. All the synthesised spiro-oxindoles exhibit significant antimicrobial activity.     

Synthesis and antimicrobial studies of hydroxylated chalcone derivatives with variable chain length

A series of (E)-1-(4-alkyloxyphenyl)-3-(hydroxyphenyl)-prop-2-en-1-one have been successfully synthesised via Claisen-Schmidt condensation. The synthesised chalcone derivatives consisted of hydroxyl groups at either ortho, meta or para position and differed in the length of the alkyl groups, C (n) H(2) (n) (+1,) where n?=?6, 10, 12 and 14. The structures of all compounds were defined by elemental analysis, IR, (1)H- and (13)C-NMR. The antimicrobial studies were carried out against wild-type Escherichia coli American Type Culture Collection 8739 to evaluate the effect of the hydroxyl and the alkyl groups of the synthesised chalcones. All the synthesised compounds have shown significant antimicrobial activities. The optimum inhibition was dependent on the position of the hydroxyl group as well as the length of the alkyl chains.     

Self-assembly of azo molecules to mesogenic phasmid-like materials through inter-molecular hydrogen bonding

A series of acid-functionalised new azo compounds was synthesised and characterised. The constituent molecules self-organise to form dimers through inter-molecular hydrogen bonding, resulting in phasmid-like compounds. This was once considered to be a promising molecular architecture to form biaxial nematic phases. The mesomorphic properties of these new azo compounds were studied using polarising optical microscopy, differential scanning calorimetry and X-ray diffraction. Investigations revealed that these compounds form nematic and columnar mesophases. A few more compounds were synthesised by replacing the??N=N- linkage in these compounds with??CH=N- and??COO- to study the effect of different linkages on the mesomorphic properties in such molecular systems. All were found to be liquid crystalline. The compounds with a??N=N- linkage are more conducive to mesomorphism and are thermally very stable. The effect of number of alkoxy chains on the mesomorphic properties of this system was also studied. To the best of our knowledge, at present, only a handful of phasmid-like mesogenic compounds, formed by the intermolecular hydrogen bonding, are known.     

New highly anisotropic liquid crystal materials for high-frequency applications

We report on the developed liquid crystal (LC) compositions with large optical anisotropy and low melting point on the basis of synthesised quaterphenyl and quinquiphenyl LC compounds containing lateral substituents. Optical and dielectric anisotropies of synthesised compounds were studied to select the most optimal compounds for high-frequency applications. As a result of the research, base matrices with a wide range of the nematic phase were developed and their mesomorphic and physicochemical properties were investigated. Based on the experimental data, the influence of various fragments of molecules on the magnitude of permittivity in the high-frequency region, as well as on the loss tangent of LCs was established.     

Synthesis of polynitrogenated analogues of glucopyranoses from levoglucosan

Polynitrogenated analogues of glucopyranoses were synthesised from levoglucosan. These compounds are useful intermediates for the synthesis of new aminoglycoside mimetics.     

Synthetic approach to grayanotoxins and asebotoxins: a new construction of the a-homograyanotoxane ring system

The tetracyclic compounds ～3 and ～4 corresponding to A-homograyanotoxane system were synthesised by a thermolysis of the benzocyclobutene ～8, followed by a Wagner-Meerwein rearrangement of the kaurane type of compounds ～15 and ～16.     

醋酸铟化合物的合成及热稳定性研究

合成了３个新的醋酸铟化合物；Ｅｔ２ＩｎＯＡｃ，ＥｔＩｎ（ＯＡｃ）２，Ｉｎ（ＯＡｃ）３，并经元素分析，ＩＲ及ＭＳ鉴定，讨论了二乙基醋酸铟化合物受热引起的歧化反应和这些化合物的热稳定性。．     

Synthesis,characterisation, and biological activity of three new amide prodrugs of lamotrigine with reduced hepatotoxicity

Lamotrigine (LTG) is an antiepileptic drug used for the prevention of convulsions. Except several known side effects, hepatic dysfunction is also reported. Hepatotoxic side effects occur due to the dichlorophenyl moiety which develops an abnormally low level of glutathione. Depletion of glutathione causes oxidative stress and hepatic cell damage. The goal of the present study was to test the action and side effects of the three compounds synthesised and compared to LTG. Three amide prodrugs of LTG were synthesised by its reaction with N-acetylamino acids, viz, glycine, glutamic acid, and methionine. Purified synthesised prodrugs were subjected to thin layer chromatography, melting point, solubility and partition coefficients determination and characterised by UV, FTIR, ¹H and ¹³C NMR spectroscopy. The synthesised prodrugs were subjected to in vitro hydrolysis and to anticonvulsant and hepatotoxic activity studies. Significant reduction in hepatotoxicity and comparable anticonvulsant activities were obtained in all synthesised prodrugs as compared to LTG.     

Postsynthetic Exterior Decoration of an Organic Cage by Copper(I)‐Catalysed A3‐Coupling and Detection of Nitroaromatics

A new synthetic protocol based on one‐pot, copper(I)‐catalysed multicomponent reaction of formaldehyde, secondary amine and terminal alkyne has been employed to postsynthetically modify a self‐assembled nanoscopic organic cage. By employing this synthetic strategy, three new cages appended with phenyl‐, xylyl‐ and naphthyl‐acetylene moieties have been synthesised. The resulting modified cages were characterised by using a range of spectroscopic techniques. The synthesised cages were fluorescent and thus one of them was tested to explore the potential use of such compounds as chemosensors for the detection of nitroaromatics. Experimental findings suggest a high selective quenching of initial fluorescence intensity in the presence of nitroaromatic compounds. Furthermore, it has been observed that among the various nitroaromatics tested, nitrophenolic compounds have better quenching ability.     

Efficient synthesis of bis-isoxazole ethers via 1,3-dipolar cycloaddition catalysed by Zn/Zn<Superscript>2+</Superscript> and their antifungal activities

An efficient method was developed for synthesising isoxazoles. A series of novel bis-isoxazole ether compounds VI, VII and VIII were synthesised starting from different substituted aldehydes (I) via a 1,3-dispolar cycloaddition using Zn/Zn²⁺ as a catalyst; these were characterised by FT-IR, HRMS, ¹H NMR and ¹³C NMR spectroscopy. In addition, the antimicrobial properties of the synthesised products were investigated. The synthesised compounds exhibited significant antifungal activities in comparison with the standard drugs, fluconazole and itraconazole. It was found that Candida albicans was sensitive to 2-substituted phenyl bis-isoxazole ethers bearing pyridyl.     

2,2’─呋喃联吡咯型联体杂环化合物的合成

在强极性的醇酸体系中，利用Knorr－Paal反应制得了呋喃联吡咯系的13个新化合物，并进行了红外光谱、质谱、核磁共振谱及元素分析测定。     

Antibacterial,antioxidant and anthelmintic studies of inclusion complexes of some 4-arylidenamino-5-phenyl-4H-1,2,4-triazole-3-thiols

A series of 4-arylidenamino-5-phenyl-4H-1,2,4-triazole-3-thiols have been synthesised and their inclusion complexes have been prepared with β-cyclodextrin. The compounds and their inclusion complexes have been characterised by studying their physical and spectral properties. The thermodynamic stability constant and free energy of activation have been determined to know the stability of inclusion complexes. Finally, the compounds and their inclusion complexes are screened for antibacterial, antioxidant and anthelmintic activities. It is found that inclusion complexes of the newly synthesised compounds have appreciable stability and inclusion complex formation increases the antibacterial, antioxidant and anthelmintic activities significantly as compared to naked compound.     

New liquid crystals derived from thiophene connected to the 1,2,4-oxadiazole heterocycle

In this study, eight new compounds derived from thiophene were synthesised and characterised. The four symmetrical compounds contain two heterocyclic 1,2,4- oxadiazole on each side of the 2,5-disubstituted thiophene, and the four non-symmetrical compounds contain alkyne groups as a spacer replacing one of these heterocycles. Some of the compounds presented liquid crystalline properties with smectic and nematic mesophases. The non-symmetrical compounds presented low emission of blue light.     

A novel and efficient synthesis of 3,4-dihydroxyphenylacetic ester and amide derivatives/conjugates and assessment of their antioxidant activity

Phenolic acids, a sub-class of polyphenols, are widely studied. By contrary, 3,4-dihydroxyphenylacetic acid is scarcely studied. For this purpose, a series of 3,4-dihydroxyphenylacetic acid ester and amide derivatives/conjugates were synthesised for the first time. A systematic study has been performed to quantitatively identify the functional groups present in these compounds using different techniques such as ¹H NMR, ¹³C NMR and ESI MS. The synthesised compounds were evaluated for their in vitro antioxidant activity by a DPPH radical-scavenging assay. Their physico-chemical profile is also studied using Molinspiration tool. Among all tested compounds, amidoester 36 showed the best scavenging activity possessing an EC₅₀ 17 μΜ and improved physico-chemical properties compared to the parent compound.     

New para-para stilbenophanes: synthesis by McMurry coupling, conformational analysis and inhibition of tubulin polymerisation

The synthesis of a new family of methoxy-substituted [2.7]- and [2.8]paracyclophanes linked by 3-oxapentamethylene-1,5-dioxy and hexamethylene-1,6-dioxy bridges has been carried out by using the McMurry methodology. Related indole compounds were also synthesised. Olefin-to-diol ratios depended on the bridge length, the structure of the aromatic ring and the reaction conditions. Macrocyclisation, the methoxy substituents and the presence of a rigid indole moiety restricted the conformational equilibria, as observed by NMR spectroscopy and according to theoretical calculations. The synthesised compounds display micromolar tubulin polymerisation inhibitory activity. The conformational implications on the tubulin polymerisation inhibitory activity derived from the macrocyclisation when compared with combretastatins, closely related stilbenes, are also discussed.     

Synthesis of differentially protected ribitol derivatives from 3,4-O-benzylidene-d-ribono-1,5-lactone

Several differentially protected ribitol derivatives were synthesised using 3,4-O-benzylidene-d-ribono-1,5-lactone as versatile starting compounds for oligosaccharide synthesis. The obtained ribitol derivatives allow the regiospecific coupling of glycosyl donors to either of the hydroxyl groups of ribitol and can be applied for the preparation of polyhydroxylated compounds.