Journal of Chemical Research

The complex [CuL₂(OClO₃)₂] [L=2-(benzylthio)aniline] has been synthesised and its crystal structure determined. It displays a one-electron reductive response at −0.38 V versus SCE and its reactions with N₃^- and SCN^- ions give [CuL₂(N₃)₂] and [CuL₂(SCN)₂]. The copper atom in [CuL₂(OClO₃)₂] assumes a tetragonally distorted, octahedral geometry with two semicoordinated perchlorate oxygens in the axial positions. Two perchlorate ions are also linked to the amino nitrogen of other molecules by intermolecular hydrogen bonding. A plausible description of redox orbitals is given on the basis of single point density functional theory calculations.

Cupric chloride showed efficient catalytic activity for the cross coupling reaction of arylboronic acids and (hydroxyi mino)ethylcoumarins at room temperature in the presence of NEt₃ as base. A simple and convenient protocol for the synthesis of O-aryloxime ethers having the highly base sensitive coumarin nucleus is reported. O-Aryloxime ethers are important as they provide access to scaffolds for the generation of various biologically active compounds. They are potential precursors to benzofurans and benzisoxazoles.

Reaction between azides and acetylenes catalysed by ZnO nanoparticles (ZnO NPs) in solvent EtOH at room temperature provide a simple and efficient one-pot route for the synthesis of 1,4-disubstituted 1,2,3-triazoles in excellent yields. 1,2,3-Triazoles are used in various agricultural, industrial and medical fields.

A series of asymmetric semicarbazides were synthesised using 3-coumarin isocyanate, which was prepared from 3-coumarinyl azide by Curtius rearrangement, with acid hydrazides under microwave irradiation using a one-pot procedure. This method has the advantages of mild conditions, easy handling and high yields. The products, which have been characterised by analytical and spectral data, have many medicinal and agrochemical applications.

A new lycopodine alkaloid, 6α, 11α-dihydroxylycopodine, and three known compounds L20, lycoposerramine K, and huperzine A were isolated from the stems of Huperzia serrata. The structure of the new alkaloid was established by spectroscopic methods, especially two-dimensional NMR techniques.

An efficient procedure has been developed for the synthesis of 1H-indazolo[2,1-b]phthalazine-triones by the one-pot condensation of cyclohexane-1,3-dione, aromatic aldehydes and phthalhydrazides catalysed by proline triflate under solvent-free conditions. The reaction proceeds in good to excellent yields.

A three-component reaction of aldehydes, amines and allyltributylstannane was efficiently carried out to afford the corresponding homoallylic amine derivatives in the presence of 20 mol% of MgI₂ etherate [(MgI₂^*(OEt₂) _n ] under mild and neutral reaction conditions in good to excellent yields.

A series of new thiosubstituted 1,3,4-oxadiazole derivatives of coumarin were synthesised by reaction of 7-((5-mercapto-1,3,4-oxadiazol-2-yl)methoxy)-4-methyl-2H-chromen-2-one and α-haloketones by grinding, in solvent-free conditions at room temperature. The reaction was also carried out in ethanol in reflux conditions. Shorter reaction time and better yields were observed in solvent-free conditions. The structures of the compounds were characterised by IR, NMR, elemental analysis and mass spectral data. The synthesised compounds were evaluated for their in vitro antimicrobial screening on different strains of bacteria and fungi. Most of the compounds showed good to moderate activities.

Carbon–carbon bond formation is important in organic synthesis for the preparation of natural products, organic materials and polymers and so on. An efficient and mild reductive homocoupling of arylmethyl halides is now described. Treatment of various benzylic halides in the presence of zero valent iron nanoparticles (nZVI) and a catalytic amount of CuBr in air and water at room temperature afforded 1,2-diarylethanes in excellent yields.

A phytochemical study of Melicope patulinervia gave a new flavone 7-(3-methyl-but-2-enyloxy)-5-hydroxy-3,6,8-trimethoxy-3’,4'-methylenedioxyflavone and three known flavones, melibentin, 5-hydroxy-3,7,8-trimethoxy-3’,4'-methylenedioxyflavone, 5-hydroxy-3,6,7,8-tetrameth-oxy-3’,4'-methylenedioxyflavone. Their structures were elucidated on the basis of spectroscopic analysis combined with chemical methods. The antifungal activities of the isolated compounds were evaluated against four plant pathogenic fungi species.

The complex [Mn(Me₂phen)(H₂O)₃(MeOH)][NO₃]₂, (Me₂phen = 2,9-dimethyl-1,10-phenanthroline, neocuproine) has been prepared. Structural studies show that the [Mn (Me₂phen) (H₂O)₃(MeOH)] cation is a six coordinate octahedral species with bidentate Me₂phen and monodentate water and methanol ligands. The water molecules are hydrogen bonded to a Me₂phen free ligand, which is co-crystallised in a position adjacent to the Mn complex. Face-to-face π···π stacking interactions between coordinated and free Me₂phen ligand molecules generate an efficient parallel packing system in the complex, which also shows antituberculosis and antifungal activity. Photoluminescence properties are also reported.

Two new polyhydroxypregnane glycosides, namely cynotophyllosides G-H (1-2), were isolated from the roots of Cynanchum otophyllum, together with three known steroids. Their structures were established by spectroscopic methods and acid-catalysed hydrolysis. Cynanchum otophyllum also known as “Qingyangshen“ in traditional Chinese medicine, is a perennial weed which has been used locally to treat epilepsy, rheumatic pain, kidney weakness, and muscle injuries.

A Pd-catalysed cascade protocol, consisting of intermolecular O-alkylation and spontaneous intramolecular amidation, has been established for efficient synthesis of 2H-1,4-benzoxazin-3-(4H)-ones from o-halophenols and 2-chloroacetamides. A varity of substrates afford the desired products in good to excellent yields. It is particularly attractive for synthesis of a library of 2H-1,4-benzoxazin-3-(4H)-ones.

A new series of 1,4-diaryl-1,4-dihydrochromeno[4,3-c]pyrazoles have been synthesised. The target compounds and their analogues (2,4-diaryl-2,4-dihydrochromeno[4,3-c]pyrazoles) were tested for their antitumour activities in vitro against MCF-7 and HL-60 cells using the MTT method. Among these compounds, 1,4-bis(4-chlorophenyl)-1,4-dihydrochromeno[4,3-c]pyrazole was found to have potent antitumour activity in vitro with minimum IC₅₀ of 25.31 μg mL⁻¹ and 13.86 μg mL⁻¹ against MCF-7 and HL-60 cells respectively.

Aminosilane-functionalised spinel ferrite oxide (Fe₂O₃) magnetic nanoparticles have been synthesised and used as efficient heterogeneous base catalysts for the condensation of aromatic aldehydes with malonitrile and α (or β) naphthole via a three-component reaction under solvent-free conditions at 80°C. Quantitative conversion of the reactants is achieved under mild conditions. Recovery of the catalyst is easily achieved by magnetic decantation. The supported catalyst is reused four times without significant degradation in catalytic activity. Naphthopyrans are polyfunctionalised benzopyran derivatives that have many biological and pharmacological properties.

Sulfamic acid-functionalised magnetic nanoparticles have been synthesised and used as efficient heterogeneous solid acid catalysts for the condensation of aromatic aldehydes with 2-naphthol and amides (or carbamates) via three-component reactions under solvent-free conditions at 80°C. Quantitative conversion of the reactants is achieved under mild conditions. Recovery of the catalyst is easily achieved by ‘magnetic decantation’. The supported catalyst is reused four times without any significant degradation in catalytic activity.

3-(3,4,5-Trimethoxyphenyl)propanoylpyrrole and 3-(3,5-dimethoxy-4-hydroxyphenyl)propanoylpyrrole, two new amide alkaloids, were prepared from 3,4,5-trimethoxybenzaldehyde via 3,4,5-trimethoxycinnamic acid and the corresponding dihydroacid. This route is simple and the reaction conditions are mild.