Journal of Chemical Research

Synthesis of 2-(2-hydroxybenzoyl)-4H-furo[3,2-c]chromen-4-one has been accomplished by the reaction of 3-halochromone with 2-aminochromone. In this reaction, 2-aminochromone acts as a masked 4-hydroxycoumarin.

A three-component and one-pot reaction between 2,6-diaminopyridine or 1,2-diaminobenzene and ammonium thiocyanate with the subsequent addition of an aroyl chloride afforded the bis-1-(aroyl)-3-(aryl)thiourea in excellent yields. It was important to make the thiocyanate derivatives first and then to use those to prepare the thiourea derivatives.

Oxidative Heck coupling reactions of arylboronic acids with olefins were carried out in the presence of the polystyrene-immobilised phenanthroline palladium(II) complex using air as a co-oxidant to afford the Heck coupling products in high yields under base-free conditions. This heterogeneous palladium catalyst can be recovered by simple filtration and used for several times without loss of activity or selectivity.

A novel pH-sensitive near-IR (NIR) fluorescent dye was synthesised and utilised in the preparation of fluorescent polystyrene microspheres. Their photochemical properties, as well as the pH-dependent optical properties were investigated and showed high sensitivity to changes of pH in the range of 3.3–8.1. The fluorescence became stronger with the increase in pH. Importantly, the microspheres were able to work in aqueous media, which is highly valuable for use in biological applications.

Use of imidazolium ionic liquids [Bmim][CF₃COO] and [Bmim]OH as a catalyst for synthesis of 3-arylidene(thio)chroman-4-ones by the condensation of (thio)chroman-4-ones and aromatic aldehydes under microwave irradiation conditions. A series of 3-arylidene(thio)chroman-4-ones were obtained as the only product and considerable increase of yield was founded within short time. The products 3-arylidene(thio)chromanones were assigned the (E)-configuration based on ¹H NMR spectroscopic data.

In the absence of any solvent, a series of spiro-2-amino-4H-pyrans derivatives were synthesised via the three component reaction of malononitrile and α-methylencarbonyl compounds/enol with 9,10-phenanthroquinone or ace-naphthenequinone using 1-butyl-3-methylimidazolium hydroxide ([bmim][OH]) as a basic ionic liquid catalyst. This method has some distinct advantages such as mild reaction conditions, short reaction time and is environmentally friendly.

A carbene-Pd(II) complex and a carbene-Rh(I) complex, both derived from commercially available L-(–)-menthol, have been synthesised, characterised and their X-ray single-crystal structures determined.

An efficient and metal-free method was developed to synthesise 3-sulfenylindoles via the iodine-mediated electrophilic cyclisation of 2-alkynylanilines with disulfides. In the presence of I₂, various 3-sulfenylindoles were obtained in moderate to high yields.

Investigation of an endophyte Bacillus subtilis isolated from Angelica sinensis, has led to the isolation of a new phenylpentanamine alkaloid, 5-phenylpentan-1,3,4-triamine. Its structure was elucidated by chemical and spectroscopic means. This is the first report of the occurrence of a natural phenylpentanamine alkaloid.

Solvothermal reactions of Zn(NO₃)₂·6H₂O, 1,4-benzenedicarboxylic acid (H₂BDC) and 2,4,6-tris(pyrazol-1-yl)-1,3,5-s-triazine, yielded a new coordination polymer [Zn(BDC)(pz)·H₂O]_n (pz= pyrazole). The in situ methanolysis reaction of 2,4,6-tris(pyrazol-1-yl)-1,3,5-s-triazine with pyrazole and 2,4,6-trismethoxy-1,3,5-triazine was confirmed by their single-crystal structures. [Zn(BDC)(pz)·H₂O]_n was characterised by elemental analysis, IR, powder X-ray diffraction, photoluminescence and thermogravimetric analyses.

The specific rates of solvolysis have been determined for chloromethyl ethyl ether (3) and chloromethyl octyl ether (4) at −10.0 °C and for chloromethyl methyl sulfide (5) at 25.0 °C in a variety of pure and binary solvents. These values were used for a correlation analysis treatment using the extended Grunwald–Winstein equation incorporating literature values for solvent nucleophilicity (N_T) and solvent ionising power (Y_Cl). Appreciable values were found for the sensitivities towards changes in both N_T and Y_Cl values. Using a literature specific rate of hydrolysis at 25.0 °C for fluoromethyl methyl ether (2), the required value for chloromethyl methyl ether (1) was obtained from use of N_T and Y_Cl values and the sensitivities for 3 to changes in their values, to adjust an experimental specific rate value for 1 in 100% ethanol to the corresponding value in 100% water. In this way, an estimated k_Cl/k_F of 1.2 × 10⁵ was obtained, essentially identical to values for the solvolyses of tert-butyl halides. A unimolecular mechanism for the solvolyses, with appreciable nucleophilic solvation of the developing carbocation, is proposed. Electronic supplementary information provides, for several solvents, specific rates of solvolysis for 3, 4, and 5 at additional temperatures and the calculated activation parameters.

Tetrasubstituted zinc, cobalt, nickel, copper and lead phthalocyanines bearing four 12-membered diazadithia macrocyclic moieties on peripheral positions have been synthesised by cyclotetramerisation reaction of 1,10-ditosyl-1,2,3,5,6,8,9,10-octahydrobenzo[h][1,4,7,10]dithiadiazacyclododecine-12,13-dicarbonitrile and corresponding anhydrous metal salts under microwave irradiation. The thermal stabilities of the phthalocyanine compounds have determined by thermogravimetric analysis.

A new series of substituted 4-methyl-5-(arylazo)-2-[N‘-(6,7,8,9-tetrahydro-benzocyclohepten-5-ylidene)-hydrazino]-thiazoles and 5-(arylhydrazono)-2-[N‘-(6,7,8,9-tetrahydro-benzocyclohepten-5-ylidene)-hydrazino]-thiazol-4-one were prepared by reaction of hydrazonoyl chlorides with a thiosemicarbazone derivative. The tautomeric structures of the products were studied using electronic absorption and NMR spectroscopy. The site-selectivities of the reactions of hydrazonoyl halides with benzocyclohepten-5-one hydrazone were also investigated. In addition, the antimicrobial activity of some of the products was evaluated. Many derivatives have promising activities against antibacterial and antifungal species.

A novel phthalocyanine bearing oxygen donor atoms on the peripheral positions has been synthesised by cyclotetramerisation of (E)-4-(4-cinnamoylphenoxy) phthalonitrile and its nickel, zinc, cobalt, copper and lead derivatives prepared. The thermal stabilities of the phthalocyanine compounds have been determined and their possible biological activities (antibacterial, anticandidal and antifungal) studied. The effects of substituent on the electrochemical and in situ spectroelectrochemical behaviour of cobaltphthalocyanine have been investigated and an in situ electrocolorimetric method was applied to investigate the colour of the electrogenerated anionic and cationic forms of the complex.

An efficient procedure for the synthesis of biaryls was catalysed by Fe(acac)₂ and zinc powder in carbon tetrachloride solution at 60 °C using arenediazonium salts is reported. Symmetrical bi-aryl molecules with various substituents on the phenyl ring (methyl, trifluoromethyl, halogen, nitro, methoxyl) were synthesised in good yields in a short time under air. Zinc powder was used as reductant in the reaction to facilitate the regeneration of the iron(II) catalyst.

A convenient synthesis of 2,6-dihydroxynaphthalene from 6-bromo-2-naphthol has been achieved with high overall yield (52%) and good purity (95.7%) based on the conversion of 6-(methoxymethoxy)-2-naphthaldehyde to 6-(methoxymethoxy)-2-naphthol formate by a Baeyer–Villiger oxidation-rearrangement. Compared with the reported methods, the reaction conditions are milder and the work-up of each step is much simpler. Moreover, 6-bromo-2-naphthol as the starting material for the synthesis is readily available.

The asymmetric synthesis of both (R)-and (S)-arundic acid has been achieved via the key step of a stereoselective alkylation reaction using non-cross-linked polystyrene (NCPS) supported (4R)- and (4S)-2-phenylimino-2-oxazolidine as chiral auxiliaries. This method is efficient (both enantiomers were obtained in 99% ee and 60% overall yield) and the chiral auxiliaries can be recovered quantitatively by simple filtration.

The ligand 3-(2-pyridyl)pyrazol-1-yl acetic acid (HL) has been prepared and the complexes [Ni(L)(N₃)] _n and [Cu(L‘)₂(H₂O)₂] _n [HL‘ = 3-(2-pyridyl)pyrazole] have been synthesised by reaction of HL and NaN₃ with NiCl₂·6H₂O and CuCl₂·2H₂O under hydrothermal condition. Single-crystal X-ray diffraction analysis shows that [Ni(L)(N₃)] _n possesses a 1D infinite chain structure, which further forms a 2D supramolecular framework connected by π···π weak interactions, and [Cu(L‘)₂(H₂O)₂] _n is linked to form a 1D chain by π···π weak interactions, then to a 2D supramolecular structure by weak C–H···O interactions.