Synthesis of arylboronates via Cp*RuCl-catalyzed cycloaddition of alkynylboronates

In the presence of 5-10 mol% Cp*RuCl(cod), 1,6- and 1,7-diynes were allowed to react with an ethynylboronate at ambient temperature to give rise to bicyclic arylboronates in 64-93% isolated yields. 1,6-Diynes bearing a boronate terminal also underwent cycloaddition with monoalkynes to give the corresponding bicyclic arylboronates.     

Synthesis of a (piperazin-1-ylmethyl)biaryl library via microwave-mediated Suzuki-Miyaura cross-couplings

Boc-protected (piperazin-1-ylmethyl)biaryls have been synthesised from (Boc-piperazin-1-ylmethyl)phenylboronic acid pinacol esters via a microwave-mediated Suzuki-Miyaura coupling with aryl bromides viz. 1-bromo-, 2-, 3- or 4-nitrobenzene or 2-bromo-5-nitropyridine. Judicial removal of the protecting group on the piperazine, or facile reduction of the nitro group on the biaryl system enabled the manipulation of two points of functionality in order to diversify the scope of the resulting biaryl library.     

Ru(II)-catalyzed chemo- and regioselective cyclotrimerization of three unsymmetrical alkynes through boron temporary tether. One-pot four-component coupling via cyclotrimerization/Suzuki-Miyaura coupling

The Ru(II)-catalyzed [2+2+2] cyclotrimerization of alkynylboronates, propargyl alcohol, and terminal alkynes proceeded chemo- and regioselectively to give rise to arylboronates, which were subjected to Suzuki-Miyaura cross-coupling with aryliodides to afford highly substituted biaryls in 53-76% yields.     

Single-flask preparation of polyazatriaryl ligands by sequential borylation/Suzuki-Miyaura coupling

We report a convenient single-flask methodology for the preparation of polyazatriaryl products with relevance to luminescence, catalysis, and pharmacology. The diborylation of 1,3-dibromobenzenes and double Suzuki-Miyaura coupling produces 1,3-diheteroarylbenzenes. Similarly, borylation of heteroaryl halides and double coupling to 2,6-dichloropyridine produces 2,6-diheteroarylpyridines. This methodology appears general in producing challenging polyheteroaryl targets as long as the boronic esters have no ortho heteroatoms and coupling avoids adjacent oxygens.     

An expedient synthesis of ellipticine via Suzuki-Miyaura coupling

A simple and efficient total synthesis of ellipticine was developed via the Suzuki-Miyaura coupling of sterically sensitive 2-hydroxybenzeneboronic acid with a multifunctional aryl halide using Pd(OAc)₂ as a catalyst and Cu(OAc)₂·H₂O as an additive in DMSO/H₂O as a key step followed by double N-arylation and cyclization.     

Synthesis of 5-arylhistidines via a Suzuki-Miyaura cross-coupling

Microwave irradiation efficiently promoted the Suzuki-Miyaura reaction of a 5-bromohistidine with various arylboronic acids in the presence of a palladium catalyst. This methodology allowed the synthesis of histidines substituted at position 5 of the imidazole ring with a phenyl, a substituted phenyl, a pyridyl or a thienyl ring. The corresponding 5-arylhistidines were obtained in moderate to good yields.     

Cp(*)RuCl-catalyzed formal intermolecular cyclotrimerization of three unsymmetrical alkynes through a boron temporary tether: regioselective four-component coupling synthesis of phthalides

Highly substituted phthalides were efficiently synthesized by sequential Cp(*)RuCl-catalyzed cyclotrimerization of alkynylboronates, propargyl alcohols, and terminal alkynes and palladium(II)-catalyzed carbonylation of the resultant arylboronates. The intermediate arylboronate was isolated and unambiguously characterized by X-ray crystallography. The perfect regioselectivity of the ruthenium-catalyzed formal intermolecular cyclotrimerization was discussed on the basis of the density functional calculations of a boraruthenacycle intermediate.     

Synthesis of bis-8-hydroxyquinolines via an imination or a Suzuki-Miyaura coupling approach

Bis-8-hydroxyquinolines represent an important yet underexplored class of potential ligands for the preparation of various coordination polymers, which can be used in a plethora of applications. In this work, the synthesis of two types of bis-8-hydroxyquinolines, prepared via either an imination or a Suzuki-Miyaura coupling approach, as well as their analysis is discussed. Imination was pursued through the condensation of quinolinecarbaldehydes with diamines or aminoquinolines with dialdehydes, and the Suzuki-Miyaura coupling reactions were evaluated using a bromoquinoline substrate and diboronic acids.     

A novel ditopic ring-expanded N-heterocyclic carbene ligand-assisted Suzuki-Miyaura coupling reaction in aqueous media

A series of seven-membered ditopic ring-expanded N-heterocyclic carbene (dre-NHC) precursors, bearing sterically demanding and electron-rich aryl groups, were synthesised in moderate yields via the reaction of 1,2,4,5-tetrakis(bromomethyl)benzene with the corresponding N,N′-diarylformamidines in the presence of K₂CO₃ in acetonitrile under an air atmosphere. All new compounds were characterised by HRMS, NMR spectroscopy, and microanalysis, as well as X-ray crystallography for compound 1c. The development of an efficient catalytic system for the Suzuki-Miyaura coupling reaction of aryl chlorides with various boronic acids was also investigated using the in situ generated dre-NHC ligands.     

Solid-phase synthesis of 5-arylhistidines via a microwave-assisted Suzuki-Miyaura cross-coupling

Microwave irradiation efficiently promoted the solid-phase Suzuki-Miyaura reaction of a 5-bromohistidine with various arylboronic acids in the presence of a palladium catalyst. This methodology allowed the synthesis of peptides bearing a histidine residue substituted at position 5 of the imidazole ring with a phenyl, a substituted phenyl, a pyridyl, or a thienyl ring, as well as with the benzene ring of a tyrosine residue.     

One-pot conversion of 1,1-dibromoalkenes into internal alkynes by sequential Suzuki-Miyaura and dehydrobromination reactions

A protocol for the one-pot synthesis of internal alkynes from 1,1-dibromoalkenes is reported. The method is hinged upon the Suzuki-Miyaura cross-coupling of 2-aryl- or 2-heteroaryl-1,1-dibromoalkenes with aryl or heteroaryl boronic acids or borate esters followed by dehydrobromination of the intermediate coupled products. Yields up to 89% were obtained.     

Intramolecular arylation of benzimidazoles via Pd(II)/Cu(I) catalyzed cross-dehydrogenative coupling

Electron poor benzimidazole substrates were arylated via an intramolecular cross-dehydrogenative coupling (CDC) reaction. These CDC reactions were catalyzed by a Pd(II)/Cu(I) catalyst system, capable of producing moderate yields on a large library of substrates. The substrate scope consisted of tethered arene-benzimidazoles that upon coupling, produced a fused polycyclic motif.     

A one-pot,two-step synthesis of 3-deazacanthin-4-ones via sequential Pd-catalyzed Suzuki-Miyaura and Cu-catalyzed Buchwald-Hartwig reactions

3-Deazacanthin-4-one and nine analogues, including the 8-aza analogue, were prepared rapidly and in high yields from 8-iodoquinolones and 2-chloro(het)arylboronic acids. The strategy involves construction of the central B ring via concomitant Pd-catalyzed Suzuki-Miyaura CC and Cu-catalyzed Buchwald-Hartwig CN coupling reactions.     

Pd nanoparticles supported on amphiphilic porous organic polymer as an efficient catalyst for aqueous hydrodechlorination and Suzuki-Miyaura coupling reactions

Developing efficient and recyclable heterogeneous catalysts for organic reactions in water is important for the sustainable development of chemical industry. In this work, Pd nanoparticles supported on DABCO-functionalized porous organic polymer was successfully prepared through an easy copolymerization and successive immobilization method. Characterization results indicated that the prepared catalyst featured big surface area, hierarchical porous structure, and excellent surface amphiphilicity. We demonstrated the use of this amphiphilic catalyst in two case reactions, i.e. the aqueous hydrodechlorination and Suzuki-Miyaura coupling reactions. Under mild reaction conditions, the catalyst showed high catalytic activities for the two reactions. In addition, the catalyst could be easily recovered and reused for several times. Also, no obvious Pd leaching and aggregation of Pd nanoparticles occurred up during the consecutive reactions.     

铃木偶联反应构筑卟啉阵列的研究进展

卟啉阵列是通过桥接单元或键组装而成的多卟啉体系,其电子性质取决于桥接单元以及卟啉连接的位置。由于电子相互作用的卟啉阵列在光电子器件、传感器、光伏电池、非线性光学材料以及光动力治疗的染料等方面的潜在应用价值,在过去的几十年中,科学家们对其进行了大量探索。卟啉阵列的构筑主要包括非共价组装与共价组装两种方式,前者相对容易但构筑的阵列稳定性较差,后者相对较难但构筑的阵列稳定性较好。铃木偶联是指用零价钯催化卤代烃与烃基硼酸或硼酸酯交叉偶联的反应,它是构筑结构多样、性质各异的卟啉阵列的有效手段。本文主要对其近年来在构筑多卟啉阵列方面的研究进展进行综述。最后,展望了铃木偶联构筑卟啉阵列的发展趋势。     

Suzuki-Miyaura coupling in the presence of (2,2,2-triferrocenylethyl)diphenylphosphane

The electron rich and sterically bulky title phosphane was prepared and efficiently applied in the palladium catalyzed Suzuki-Miyaura cross-coupling reaction. With electron rich aryl chlorides and bromides the yields and reaction times were significantly improved by microwave heating.     

Suzuki-Miyaura coupling for general synthesis of dehydrocoelenterazine applicable for 6-position analogs directing toward bioluminescence studies

Synthesis of coelenterazine analogs is in recent demand to supply more luminescent compounds with reasonable stability as substrate for the photoprotein manipulated in a living cells or particular organelle. There are limited methods for the synthesis of 6-substituted coelenterazine due to the route and instability of the compounds under the existing conditions. This paper describes six examples including Suzuki-Miyaura cross coupling reaction with reactive triflate (unstable) and stable tosylate intermediates of the imidazo[1,2-a]pyrazin-3-one. Five examples of 2-amino-3-benzyl-5-O-Tf-pyrazine are also discussed. The product coelenterazine analogs are obtained in the form of dehydrocoelenterazine, which is the substrate of a squid photoprotein, symplectin.     

Parallel strategies for the synthesis of annulated pyrido[3,4-b]indoles via Rh(I)- and Pd(0)-catalyzed cyclotrimerization

Two different pathways for the synthesis of annulated pyrido[3,4-b]indoles are reported using metal-catalyzed cyclotrimerization reactions. A stepwise process using Rh(I)-catalysis in the final step of the synthesis and a multicomponent, tandem catalytic approach using Pd(0)-catalysis both lead to complex nitrogen-containing heterocycles in good yields. Substituent effects are investigated for both pathways, demonstrating that the Pd(0)-catalyzed approach is more sensitive to electron-withdrawing groups.     

Suzuki-Miyaura coupling on heterogeneous palladium catalysts

Summary Five supported heterogeneous Pd catalysts have been prepared, characterized and found to be active and selective in the Suzuki-Miyaura coupling of boronic acids, and aromatic iodo and bromo compounds to form the corresponding biaryls in high selectivities. Reaction conditions, namely, the solvent, base (triethylamine, Na₂CO₃, Cs₂CO₃) and tetrabutylammonium chloride as an additive are shown to have profound effects on catalyst performance.</o:p>     

One-pot synthesis of substituted indolines via a copper-catalyzed sequential multicomponent/C-N coupling reaction

One-pot synthesis of 2-(N-sulfonylimino)indolines has been developed. The procedure combines the copper-catalyzed three-component reaction of sulfonyl azides, o-bromophenylacetylenes, and amines and the copper-catalyzed intramolecular C-N coupling in one sequence, which afforded the products in moderate to good yields. The resulting 2-(N-sulfonylimino)indolines could be easily transformed to pharmaceutically valuable oxindoles (indolin-2-ones).