Journal of Chemical Research

A series of magnetic, ionic-substituted tetrapyridyl metalloporphyrins, [tetrakis(N-octyl-4-pyridinium)–metal–porphy-rin][tetrabromoferrate(III)]₄ (metal=iron, cobalt, manganese, copper or zinc), have been synthesised. All compounds show weak ferromagnetic behaviour at room temperature and respond to an external neodymium magnet.

Amidoxime fibres–nickel(0) complexes [Ni(0)–AOFs] were synthesised by combining a Ni²⁺-solution with amidoxime fibres and reduced by NaH₂PO₂. The Ni(0)–AOFs are inexpensive phosphine-free recyclable heterogeneous catalysts for the Suzuki coupling reaction of aryl halides with phenylboronic acid to provide the corresponding biphenyls in high yields. The heterogeneous catalyst can be readily recovered by simple filtration and reused several times without significant loss of activity.

The reactive intermediate produced in the reaction between pyridines and dialkyl acetylenedicarboxylates was trapped by aryl isothiocyanates to afford 2-thioxo-1,9a-dihydro-2H-pyrido [1,2,a]pyrimidine derivatives in good yields.

The potassium thiocyanate-catalysed reaction of dialkyl acetylenedicarboxylates with indane-1,3-dione in acetone, led to dialkyl 4-oxo-3,4-dihydro-2H-indeno[1,2-b]furan-2,3-dicarboxylates in good yields. The presented one-pot method is simple and effective with mild conditions.

The phenylboronic acid-catalysed reaction of an N-arylglycine ethyl ester with various carboxylic acids, including N-acyl-N-phenylglycines, directly affords an amide or a dipeptide in 13–73% yields.

1-Aryl-1H-1,2,3,4-tetrazoles were synthesised by the solvent-free reactions of aryl amines, sodium azide and triethyl orthoformate using FeCl₃–SiO₂ as an effective heterogeneous catalyst under conventional and ultrasound irradiation conditions. This method has the advantages of high yields, simple methodology and easy work-up. The catalyst can be recovered by simple filtration and reused delivering good yields.

Acetylation of D-glucosamine catalysed by sulfuric acid and N-phthaloylation of the glucosyl acetate yielded 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-α-D-glucopyranose. This gave the corresponding pure β-glucosyl chloride upon treatment with PCl₅-BF₃. An anomeric chlorination with thionyl chloride combined with the Lewis acids (ZnCl₂, SnCl₄ and BiCl₃) resulted in an α/β anomer mixture.

Pd(OAc)₂/1,10-phenanthroline-catalysed addition of potassium phenyltrifluoroborate to aliphatic dinitriles in 2-MeTHF has been developed, achieving diphenyl diones in moderate to excellent yields. The scope of the developed approach was successfully explored toward the addition of potassium phenyltrifluoroborate to aromatic dinitriles. Additionally, a plausible pathway for the formation of the diones has been proposed.

A series of novel (1-arylmethyl-3-aryl-1H-pyrazol-5-yl)(4-arylpiperazin-1-yl)methanone derivatives were synthesised. Preliminary study of the structure–activity relationship revealed that 4-chlorophenyl, 4-tert-butylphenyl, 4-fluorophe-nyl and 3-methoxyphenyl had a promising effect on the antifungal activity.

Michael reactions of indoles with α,β-unsaturated ketones were carried out under microwave irradiation in water, affording the corresponding products in good to excellent yields. The calix[6]arene sulfonic acids bearing pendent aliphatic chains, as efficient surfactant-type acid catalysts, can be recovered after simple work-up and reused directly several times without loss of catalytic activity.

A highly efficient procedure for preparing 2-acylpyrroles and its derivatives is described. The products were obtained through regioselective Friedel–Crafts reactions of pyrroles and its derivatives with alkyl or aryl acid chlorides catalysed by zinc oxide under solvent-free conditions. This method has the advantages of green chemistry, operational simplicity, solvent-free conditions, and recoverable catalyst.

The specific rates of solvolysis of α, p-dichloroanisole (chloromethyl p-chlorophenyl ether, 1) have been measured conductimetrically in a variety of hydroxylic solvents. In three typical solvents, at 25.0 °C, the rate is 20–45 times greater than for the corresponding sulfide. In a comparison with the solvolysis of a substrate with an alkyl group replacing the aryl group, chloromethyl ethyl ether (2), at −10.0 °C in four typical solvents, 1 reacted considerably more slowly than 2, by a little over four orders of magnitude. An extended Grunwald–Winstein equation treatment of the specific rates of solvolyses in 24 solvents at 25.0 °C leads to an l value of 0.68 ± 0.04 and an m value of 0.59 ± 0.03 (l/m = 1.15). Appreciable nucleophilic assistance in the progress to the transition state is indicated and either nucleophilic solvation to an ionisation process or a loose S_N2 transition state with extensive bond-breaking accompanied by a smaller degree of bond-making lead to an appropriate transition state.

The synthesis of new bis-phenanthrimidazole derivatives in one-pot four-component reaction from 9,10-phenanthra-quinone, aromatic aldehydes, 4,4'-diaminodiphenyl ether and ammonium acetate is described. These new compounds were subsequently studied for their fluorescence properties.

The metalloporphyrin [(ZnTPP)₂(μ₂-4,4'-bipy)], (H₂TPP = 5,10,15,20-tetraphenyl-21H,23H-porphyrin; 4,4'-bipy = 4,4'-bipyridine), has been synthesised via a solvothermal reaction and structurally characterised by single-crystal X-ray diffraction. It features a planar porphyrin macrocycle and an embedded Zn^II ion coordinating to four pyrrole nitrogen atoms and one 4,4'-bipy nitrogen atom. A photoluminescent and theoretical study shows that the complex exhibits an emission in the red region, attributed to ligand to ligand charge-transfer.

New derivatives of polyfunctional pyrazolo[3,4-b]pyridines were synthesised via a regioselective one-pot three-component reaction of 3- (cyanoacetyl)indole, 5-amino-3-methylpyrazole and arylaldehydes in excellent yields using Fe³⁺-montmorillonite as a reusable catalyst under conventional conditions and ultrasonic irradiation. In particular, valuable features of this method include high reaction rate, employment of a reusable catalyst, straightforward procedure, the easy work-up of the products and mild reaction conditions. The antibacterial activities of the synthesised products were examined which showed promising activities.

A convenient and efficient synthetic approach for the synthesis of 5-substituted 3-aryl-4,5-dihydroisoxazoles is reported. In the presence of triethylamine, a series of hydroximoyl chlorides were transformed into nitrile oxides, followed by reaction with N-vinyl-2-pyrrolidinone (or 4-vinylpyridine) by a 1,3-dipolar cycloaddition to give novel 4,5-dihydroisoxazole derivatives.

Preparation of a series of 3-cyano-2-(1H-indol-3-yl)-6-(9-butylcarbazol-3-yl)pyridine derivatives through the one-pot four-component coupling of aromatic aldehydes, 1-(9-butylcarbazol-3-yl)ethanone, 3-(cyanoacetyl)indole and ammonium acetate is reported. All these compounds were obtained in good yield and their structures were confirmed by ¹H NMR and IR spectroscopy and by elemental analysis.

Acid hydrazides or araldehyde N-acylhydrazones can be converted in good yields to, respectively, symmetrical or unsymmetrical, 2,5-disubstituted 1,3,4-oxadiazoles at 60 °C by a Bu₄NI-catalysed procedure which requires the presence of a base and 2.5 equiv. of t-butyl hydroperoxide.

A novel method for 1,2,4-triazole-3-thiones formation is established using the reaction of ammonium thiocyanate and aroyl chlorides with acylhydrazides under solvent-free conditions to afford triazole-3-thiones in good yields.