A one-pot tandem sequential protocol for efficient synthesis of a series of new pyranopyrazole derivatives has been developed involving Suzuki coupling of 4-bromobenzaldehyde and arylboronic acids followed by a four-component reaction from readily available ethyl acetoacetate, malononitrile, and hydrazine hydrate. All of the products were fully characterized by melting point, FTIR, ¹H NMR, and ¹³C NMR spectroscopy, and HRMS. The structure of one of the products was further established by X-ray diffraction analysis. This method should provide a useful strategy for the construction of pyranopyrazole heterocycles.

A novel palladium(II) carboxymethylcellulose (CMC-Pd^II) was prepared by direct metathesis from sodium carboxymethylcellulose and PdCl₂ in aqueous solution. Its catalytic activities were explored for Heck–Matsuda reactions of aryldiazonium tetrafluoroborate with olefins, and Suzuki–Miyaura couplings of aryldiazonium tetrafluoroborate with arylboronic acid. Both reactions proceeded at room temperature in water or aqueous ethanol media without the presence of any ligand or base, to provide the corresponding cross-coupling products in good to excellent yields under atmospheric conditions. The CMC-Pd^II and carboxymethylcellulose-supported palladium nanoparticles (CMC-Pd⁰) formed in situ in the reactions were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, inductively coupled plasma atomic emission spectrometry, and scanning and transmission electron microscopies. The homogeneous nature of the CMC-Pd⁰ catalyst was confirmed via Hg(0) and CS₂ poisoning tests. Moreover, the CMC-Pd⁰ catalyst could be conveniently recovered by simple filtration and reused for at least ten cycles in Suzuki–Miyaura reactions without apparently losing its catalytic activity. The catalytic system not only overcomes the basic drawbacks of homogeneous catalyst recovery and reuse but also avoids the need to fabricate palladium nanoparticles in advance. Copyright © 2015 John Wiley & Sons, Ltd.

The PdCl(C₃H₅)(dppb)/KOAc system was found to be effective for the direct regioselective C-5 arylation of 3-acetylpyrroles with ortho-substituted aryl bromides. This procedure has been found to be tolerant to a variety of functional groups at C-2 of the aryl bromide such as methyl, formyl, nitrile, nitro, hydroxymethyl, chloro, fluoro or trifluoromethyl. The sequential direct C-5 arylation followed by C-2 arylation of such 3-substituted pyrroles allows the synthesis of 2,5-diaryl-3-acetylpyrroles in high yields.

A new kind of silica-supported third-generation dendrimers capped by 1,4-diaza-bicyclo[2.2.2]octane (DABCO) group-stabilized palladium(0) nanoparticles, and their enhanced catalytic activity in Suzuki–Miyaura and Mizoroki–Heck reactions in excellent yield under mild conditions, was reported. The resulting silica-supported dendrimer-stabilized palladium(0) nanoparticles with a particle size of 10–20 nm were prepared in situ by treatment with PdCl₂ and hydrazine in ethanol at 60 °C for 24 h. The catalyst as prepared was characterized by FT-IR, X-ray diffraction, thermal analysis, elementary analysis (EA), scanning electron microscopy and transmission electron microscopy. Recycling experiments showed that the catalyst could be easily recovered by simple filtration and reused for up to five cycles without losing its activity. Copyright © 2012 John Wiley & Sons, Ltd.

A novel one-pot synthesis of biaryl derivatives has been developed starting from bromobenzaldehyde and phenylboronic acid in the presence of activated methylene compounds via sequential Suzuki coupling/Knoevenagel condensation in aqueous isopropanol medium at room temperature. Significantly, this strategy afforded a straightforward and efficient approach to construct original biaryls in which a new carbon double bond bound to activated moieties such as nitrile, ester and amide is formed from three simple substrates in a one-pot procedure. Moreover, a wide scope of substrates could effectively participate in the process affording the target products in moderate to excellent yields.

An efficient, clean, and environmentally benign synthesis of spirooxindole derivatives by one-pot three-component reaction of isatins, malononitrile, and carbonyl compound in the absence of catalysis in water was described. A variety of spirooxindole derivatives were obtained with excellent yields within short reaction time. This novel protocol has the advantages of convenient operation, low cost, and environmental benign. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:673–677, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20723

A simple, clean, and environmentally benign three-component process for the synthesis of 4H-benzo[b]pyran derivatives using basic ionic liquid N,N-dimethylaminoethylbenzyldimethylammonium chloride ([PhCH₂Me₂N⁺CH₂CH₂NMe₂]Cl⁻) as an efficient catalyst under solvent-free condition is described. A wide range of aromatic aldehydes easily undergoes condensation with malononitrile and 5,5-dimethylcyclohexane-1,3-dione (dimedone) under solvent-free condition to afford the desired products of good purity in excellent yields. Taking into account environmental and economical considerations, the protocol presented here has the merits of environmentally benign, simple operation, convenient workup, and good yields. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:91–94, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20516