Journal of Chemical Research

A series of symmetric, silicon-linked organic fluorescent compounds with two electron-deficient 1,3,4-oxadiazole units were synthesized and characterized. The compounds possessed a V-shaped structure with a silicon atom, which weakened π–π stacking, promoting aggregation-induced emission. The compounds were fluorescent in both solution and solid-state thin films. The efficient fluorescent behavior of the materials was confirmed through optical and electrochemical measurements. The compounds displayed excellent thermal stability, with decomposition temperatures exceeding 400 °C. Amorphous films of the compounds possessed high morphological stability. These results indicate that the compounds may be promising emissive and electron-transporting materials.

A series of 12 novel methyl- and halogen-substituted bischalcones containing an azo linkage was synthesized by a Claisen–Schmidt condensation between (E)-1-{4-[(4-acetyl-2-hydroxyphenyl)diazenyl]phenyl}ethanone and various araldehydes using microwave irradiation and conventional procedures and the results were compared.

A new and efficient synthesis of 6-bromo-8-cyclopentyl-5-methyl-2-(methylsulfinyl)-pyrido[2,3-d]pyrimidin-7(8H)-one, a key intermediate of Palbociclib, starting from thiouracil was described. This protocol involved methylation, nucleophilic substitution, bromination, nucleophilic substitution, Heck reaction, ring closure, oxidation, and bromination to afford a key intermediate of Palbociclib with approximately 35% overall yield. The advantages of this developed synthetic strategy included improved overall yield, inexpensive starting materials, and readily controllable and cleaner reaction conditions.

1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][OTf]) is an efficient co-solvent and co-promoter for one-pot sequential glycosylation with the combined use of thioglycosides and trichloroacetimidates (or N-phenyltrifluoroacetimidates) donors at room temperature. One-pot glycosylation is efficient for the synthesis of triterpenoid saponins with the combined use of N-phenyltrifluoroacetimidate donors and 2-methyl-5-tert-butylphenyl (Mbp) thioglycoside donors in [emim][OTf].

The bis-oxime of acenaphthenequinone and the mono-oxime of benzil have been sulfonated by reaction with 4-methylbenzenesulfonyl chloride and propylsulfonyl chloride. The four sulfonated oximes were characterised by X-ray single-crystal structure determinations. Some photochemical decompositions were studied using a 6-W 254-nm immersion well lamp in dichloromethane. The 4-methylbenzenesulfonate bis-oxime of acenaphthenequinone and the 4-methylbenzenesulfonate mono-oxime of benzil both give 4-methylbenzenesulfonic acid upon irradiation but not 4-methylbenzenesulfinic acid. Fragmentation pathways are discussed. The possible use of these compounds as photoacid generators in polymer resists and the role of secondary reactions to liberate acid is discussed.

Treatment of a series of aromatic hydrocarbons and O-carbethoxy phenol substrates with a mixture of chlorosulfonic acid and dimethoxymethane in CH₂Cl₂ catalyzed by zinc iodide affords the corresponding chloromethyl derivatives in good to excellent yields.

A one-pot, efficient synthesis of seven novel trans-2,3-diacylated hexahydrobenzofuran derivatives has been achieved via a three-component condensation of N-(1-benzyloxycarbonylmethyl)quinolinium bromide with 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and an aromatic aldehyde in the presence of catalytic amounts of triethanolamine in water under reflux conditions. The attractive features of the method are excellent yields and high purity, short reaction times, easy work-up, and use of an inexpensive and non-toxic catalyst.

An efficient [3 + 2] cycloaddition reaction of cyanocyclopropanecarbonates and (E)-3-aryl-2-cyanoacrylates mediated by 1,8-diazabicyclo[5.4.0]undec-7-ene for the synthesis of highly functionalized cyclopentane derivatives in moderate to good yields (79%−87%) was developed. The structures of two typical products were confirmed by X-ray crystallography.

A green synthesis of variously substituted biphenyl carboxylic acids was achieved through Suzuki–Miyaura cross-coupling of a bromobenzoic acid with an aryl boronic acid using a water-soluble fullerene-supported PdCl₂ nanocatalyst (C₆₀-TEGs/PdCl₂). Yields of more than 90% were obtained at room temperature in 4 h using 0.05 mol% catalyst and 2 equiv. K₂CO₃.

Ten novel ureido-substituted 1,3-benzoxazines were synthesized in moderate yields by La(OTf)₃-catalyzed reaction of some aldehydes with four ureido-substituted 2-aminomethylphenols which were prepared by a one-pot method. Evaluation of their fungicidal activity revealed that most compounds showed moderate to good activity and one of the ureido-substituted 2-aminomethylphenols showed activity against Rhizoctonia solani and Sclerotonia sclerotiorum comparable to the control compound, chlorothalonil.

The complex [Zn(CH₃OH)₄(MCA)₂] (3-hydroxy-2-methylquinoline-4-carboxylic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal X-ray diffraction. Its solid-state photoluminescence spectrum shows an emission in the blue region, which is assigned to ligand-to-metal charge transfer on the basis of time-dependent density functional theory calculations. Solid-state diffuse reflectance measurements show the existence of a narrow optical band gap of 1.73 eV.

The sulfa-Michael/aldol cascade reaction of (Z)-2-arylmethylidene-benzo[4,5]imidazo[2,1-b]thiazol-3(2H)-ones and 1,4-dithiane-2,5-diol afforded novel 2-aryl-4-hydroxy-spiro[benzo[4,5]imidazo[2,1-b][1,3]thiazole-2,3-thiolan]-3-ones in moderate yields. The structures of all the products were characterized thoroughly by nuclear magnetic resonance, infrared and high-resolution mass spectrometry together with X-ray crystallographic analysis.

{1-[4-(n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines (n-alkoxy = O(CH₂) _n H, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.