Journal of Chemical Research

Citranaxanthin and its analogues were synthesised via a C₅ unit elongation to substituted conjugated polyenes. Their free radical scavenging activity was measured by 1,1-diphenyl-2-picrylhydrazinyl spectrophotometric methods. Results indicated that the new compounds exhibited antioxidant activities. Three new analogues had stronger antioxidant activity than citranaxanthin.

With visible-light irradiation, a simple and metal-free photocatalytic system for the synthesis of diaryl ethers from arylboronic acids and diaryliodonium salts has been developed. The reaction proceeded in high yield for a range of different substrates in the presence of eosin Y under mild reaction conditions.

The reaction of 1-trimethylsilyl-1H-imidazole with nucleophilic active phosphacumulenes afforded imidazole silyl phosphoranylidenes or imidazole phosphoranylidenes according to the reaction conditions. The reaction of hexaphenylcarbodiphosphorane with 1-trimethylsilyl-1H-imidazole resulted in the formation of silyl phosphoranylidene phosphoranyl imidazole, silyl phosphoranylidene imidazole and triphenylphosphane. Moreover, Lawesson and Japanese reagents afforded imidazole phosphinothioic thioanhydrides.

A series of novel indole derivatives linked with the 1,2,3-triazole moiety was designed, synthesised by the CuCl₂/Zn-catalysed Huisgen cycloaddition and characterised. The antifungal activity of all the prepared compounds against Colletotrichum capsici and cotton Physalospora pathogens was evaluated and the results indicated that these compounds showed inhibitory effect for fungi and the inhibition ratio of the best was up to 83.3%. The preliminary structure–activity relationship is also discussed in this paper.

The one-pot, three-component reaction between pyridine and activated acetylenes in the presence of N’-arylidenebenzohydrazide as NH-acids affords dialkyl 2-[2-(N-benzoyl-N’-arylidenehydrazino)pyridin-1(2H)-yl]but-2-endioate derivatives which has advantages such as simple work-up, and affording yield.

A new series of 2-aminothia zolo[5,4-d]pyrimidines has been synthesised by treating various amines with the new intermediate, 2,5-dichloro-7-methylthiazolo[5,4-d]pyrimidine. Sequential treatment of the amino derivatives with hydrazine hydrate and triethyl orthoesters gave thiazolo[5,4-d][1,2,4]triazolo[4,3-a]pyrimidines as derivatives of a novel heterocyclic system.

A novel turn-off fluorescent probe bearing a benzoxazole fluorophore has been synthesised and characterised. Its recognition properties towards different metal ions have been researched by spectrometry. The probe was highly selective and sensitive to Hg²⁺ and showed a complexation ratio towards Hg²⁺ of 1:1. Its fluorescence intensity varied almost linearly with the concentration of Hg²⁺ (1.6~8.6 μmol L⁻¹), and the detection limit of Hg²⁺ was estimated to be 0.68 μmol L⁻¹.

3-(Naphlhyl-1-amino)-3-oxopropanoic acid and N,N′-di(naphthyl-1-yl)malonamide were synthesised by the reaction of 1-naphthylamine with diethyl malonate under reflux. These two compounds were then separately cyclised to 4-hydroxybenzo[h]quinolin-2-(1H)-one in two different reactions in polyphosphoric acid. A series of esters and ethers of the 4-hydroxy group and some 3-substituted derivatives were prepared. The structures of the compounds were confirmed by infra-red NMR spectroscopy and elemental analysis.

An eco-friendly efficient method was developed for the synthesis of abiraterone acetate and analogues in water-PEG-400 (6:1; v/v) at 75°C from various arylboronic acids and 17-(trifluoromethanesulfonyl)oxy-3β-acetoxylandrosta-5,16-diene obtained from the 3-acetate of dehydroepiandrosterone.

A simple and efficient strategy for the synthesis of novel aryloxy-functionalised 4,4′-bi-1,2,4-triazoles was successfully explored by nucleophilic aromatic substitution of tetrachloro-4,4′-bi-1,2,4-triazole by various phenols using Cs₂CO₃ as catalyst. The syntheses were achieved in 25–94% yields.

A highly regioselective ring-opening of epoxides with acetic anhydride in the presence of hydrated disodium hydrogen phosphate and sodium hydrogen sulfate as efficient and eco-friendly reagents is described. The reactions are clean and lead to 1,2-diacetates in high to excellent yields.

4-(Benzo[d][1,3]dioxol-5-yl)-2-hydrazinyl-6-oxo-1,6-dihydropyrimidine-5-carbonitrile was utilised to construct fused heterocyclic systems, namely triazolopyrimidines, as well as non-fused heterocyclic systems such as pyrazole and dioxopyrazolidine derivatives. The antioxidant activity of the new compounds was evaluated. Most of the synthesised compounds have potent antioxidant activity.

A microwave-assisted direct coupling between aryl halides and carbon disulfide in ionic liquid [DBUH]⁺[OAc]⁻ (DBU = 1,8-diazabicyclo-[5.4.0] undec-7-ene) has been developed. The reactions are very efficient, affording the corresponding diaryl thioethers in moderate to high yields. Aryl chlorides could also be reacted with carbon disulfide using this protocol. Moreover, [DBUH]⁺[OAc]⁻ could be easily recovered and reused for several runs.

Two new di(phthalimidomethyl)-1,2,3-triazole derivatives have been synthesised using 1,3-dipolar-cycloadditions under thermal and copper catalysed conditions from N-(azidomethyl)phthalimide and N-prop-2-ynylphthalimide. The molecular structure of both starting materials was studied by X-ray crystallography. A complete DFT analysis of the alkyne and azide compounds was carried out.

An efficient and simple synthesis of 3-aryl-5-(dialkoxymethyl)-1,2,4-oxadiazoles is described. The in situ prepared amidoximes from the reaction between nitriles and hydroxylamine are condensed with alkyl 2,2-dialkoxyacetates under solvent-free conditions to produce the title compounds in excellent yields.

The alcoholysis of the epoxides of α- and β-pinene catalysed by tetracyanoethylene form the 8-alkyl ethers of trans-sobrerol and 7,8-dihydroxy-p-menth-1-ene, respectively.