3-Iodoselenophene derivatives: a versatile substrate for Negishi cross-coupling reaction

3-Iodoselenophene derivatives undergo a direct Negishi cross-coupling reaction with several organozinc compounds in the presence of a catalytic amount of Pd(PPh₃)₄ in THF at room temperature. This cross-coupling reaction proceeded cleanly under mild conditions and permitted the formation of polyaromatic compounds in good yields.     

Pd-catalyzed Negishi coupling of pyrazole triflates with alkyl zinc halides

A mild, functional group tolerant palladium-catalyzed Negishi coupling of pyrazole triflates and nonaflates with alkyl, benzyl, and aryl zinc halides has been developed. It allows quick access to 3-substituted pyrazole analogs at late stage via common synthetic intermediates.     

Highly selective mono-substitution in Pd-catalyzed cross-coupling reactions of 3,6-dichloropyridazine with organozinc compounds

Pd-catalyzed cross-coupling reactions of 3,6-dichloropyridazine (1) with benzyl, aryl, and alkyl organozinc compounds led to selective mono-substitution of one of the chlorine atoms. The subsequent cross-coupling of the resulting monochlorides with RZnCl afforded unsymmetrical 3,6-carbon-disubstituted pyridazines.     

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones with arylboronic acids

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones and arylboronic acids proceeded by the treatment with Pd(OAc)₂ in acetic acid to afford 2-aryl-1-naphthols.     

Nickel-catalyzed carbonylative Negishi cross-coupling reactions

Catalytic carbonylative Negishi cross-coupling reactions are described. This method readily provides various enones from enol triflates and diorganozinc reagents with catalytic amounts of nickel(II) chloride-4,4′-dimethoxyl-2,2′-bipyridyl under carbon monoxide atmosphere. The rate of carbon monoxide insertion is increased by the addition of lithium or magnesium halides and the use of polar solvents. Alkenyl iodides can also be used in place of enol triflates.     

Gold catalysed Suzuki-Miyaura coupling of arenediazonium o-benzenedisulfonimides

Arenediazonium o-benzenedisulfonimides have been used as efficient electrophilic partners in Au(I) catalysed Suzuki coupling reactions. The synthetic protocol is general, easy and produced either biaryls or heteroaryl arenes in good yields (51 positive examples, average yield 80%). o-Benzenedisulfonimide was recovered at the end of the reactions and was reused to prepare the starting salts for further reactions. Mechanistic insights suggest that the o-benzenedisulfonimide anion act as an electron transfer agent and promotes a catalytic cycle which does not require the presence of photocatalysts or external oxidants.     

Synthesis of chiral amino acids with metal ion chelating side chains from l-serine using Negishi cross-coupling reaction

The scope of the Negishi cross-coupling reaction of organozinc compounds derived from chiral amino acids was extended to electron rich iodoanilines and iodobenzylamines as coupling reagents. The protocol allows the direct modification of serine into phenylalanine derivatives bearing metal ion chelating ligands in their side chain, such as amino esters 6 and 7. The preparation of metal complex labeled peptides, the construction of synthetic receptors and hybrid materials are potential applications of the modified chiral amino acids.     

Oxidative addition of heteroaromatic halides to Negishi reagent and subsequent cross-coupling reactions

Heteroarylzirconocene halides were prepared via the oxidative addition of heteroaryl halides to the Negishi reagent ‘Cp₂ZrBu₂’. The palladium-catalyzed cross-coupling of the in situ generated organozirconium reagents with functionalized aryl and heteroaryl halides proceeded smoothly in the presence of CuCl to produce the cross-coupling products in high yields.     

Palladium-catalyzed desulfinylative Negishi C-C bond forming cross-couplings of sulfonyl and organozinc chlorides

Arene-, phenylmethane- and alkenesulfonyl chlorides are suitable electrophilic reagents in desulfinylative carbon-carbon bond formation cross-coupling reactions with organozinc reagents.     

Stereoselective sp-sp bond formation via Negishi cross-coupling of vinylic tellurides and 2-heteroarylzinc chlorides

The Negishi cross-coupling reaction of vinylic- and aryltellurides with heteroarylzinc chlorides catalyzed by PdCl₂/CuI is described. This cross-coupling reaction is general and permits the formation of a new sp²-sp² carbon bond in good yields and high stereoselectivity.     

Palladium-catalyzed direct cross-coupling reaction between indenes and electron-deficient alkenes

An efficient methodology for oxidative cross-coupling of indene and derivatives with electron-deficient olefins catalyzed by palladium was developed. The corresponding diene products were obtained in moderate to good yields.     

Palladium-catalyzed Suzuki cross-coupling reactions in a microemulsion

An enhancement of palladium-catalyzed Suzuki cross-coupling reactions between substrates possessing long-chain alkyl or oxyalkyl substituents in two-phase media, in the presence of sodium dodecylsulfate, is shown. Quantitative evaluations of the influence of SDS on the reaction rates were determined.     

Identification and synthesis of new sex-specific components of olive fruit fly (Bactrocera oleae) female rectal gland,through original Negishi reactions on supported catalysts

In the present study, eleven new sex-specific components extracted from female rectal gland of olive fruit flies were synthesized and identified. The quantitative determination of those components by GC and GC/EI-MS, at different moments of the insect life span, highlighted the growing trend of their secretion. While for the synthesis of saturated esters, conventional transesterification methods could be adopted, for the synthesis of unsaturated components, a Negishi cross-coupling between organozinc halides and (Z)-1-bromo-1-alkenes was developed. To the extent of our knowledge, this reaction represents the first example of supported-catalyst promoted Negishi coupling, between an alkylzinc reagent and an alkenyl halide.     

Synthesis of α-aryl-diazophosphonates via palladium-catalyzed cross-coupling of aryl iodides with diethyl diazomethylphosphonate

An efficient procedure for the Pd-catalyzed arylation of diethyl α-diazomethylphosphonate with aryl iodides is described. It can serve as a pathway for the generation of arylated diazophosphonates, which are typically difficult to access. The significance of this methodology was demonstrated via further synthetic transformations of newly synthesized diazo compounds in cyclopropanation, epoxidation, N–H and O–H insertion reactions.     

Convenient synthesis of chiral tryptophan derivatives using Negishi cross-coupling

A facile synthetic procedure for chiral tryptophan derivatives using Negishi cross-coupling reaction of serine-derived iodoalanine with 3-haloindole is described. The best result was obtained when the reaction of N-tosyl-3-bromoindole with N-Cbz-iodoalanine methyl ester was carried out by the combination of Pd₂(dba)₃ and sterically hindered ferrocenyl ligand Q-PHOS. This reaction condition not only gave the desired tryptophan derivative as high as 76% yield, but also suppressed the formation of undesired products, the dehalogenated indole and the homodimer of indole, which were difficult to separate. This reaction was extended to the synthesis of various tryptophan derivatives having substituents on the benzene ring. The characteristic of this reaction is the practical biomimetic synthesis of chiral tryptophan derivatives in one-step.     

Negishi cross-coupling of organotellurium compounds: synthesis of biaryls, aryl-, and diaryl acetylenes

A functional group tolerant palladium-catalyzed Negishi coupling of diaryl tellurides with organozinc has been developed. This methodology permits efficient preparation of biaryls, aryl acetylenes and diaryl acetylenes in moderate to good yields. A preliminary study to gain further insight into the reaction was performed using in situ ReactIR technology.     

Pd(DPEPhos)Cl2-catalyzed Negishi cross-couplings for the formation of biaryl and diarylmethane phloroglucinol adducts

Several functionalized biaryls and diarylmethanes containing the phloroglucinol subunit were synthesized in 55-85% yields using Negishi cross-couplings of 2,4,6-trimethoxyphenylzinc chloride with aryl and benzyl halides in the presence of catalytic quantities of Pd(DPEPhos)Cl₂. These simple to prepare couplings were generally complete in 1-24 h depending on the halide, and were applicable to aryl and benzyl halides containing both electron-donating and electron-withdrawing groups.     

Stereoselective synthesis of 1,3-dienylstannanes by palladium catalyzed cross-coupling reactions

(Z)-α-Bromovinylstannanes are new difunctional group reagents, which undergo palladium catalyzed cross-coupling reactions with (E)-alkenylzirconium complexes to give stereoselectively 1,3-dienylstannanes in good yields.     

Arylzinc species by microwave assisted Grignard formation-transmetallation sequence: application in the Negishi coupling

Arylmagnesium species can be efficiently generated from magnesium turnings and aryl chlorides or aryl bromides under dielectric heating conditions. Subsequent microwave assisted transmetallation using ZnCl₂-TMEDA afforded the corresponding arylzinc reagents. A sequential microwave assisted arylmagnesium formation-transmetallation-Negishi coupling protocol suitable for automated multiple parallel synthesis has been developed.     

Synthesis of non-symmetrical alkynylpyridines by chemoselective Sonogashira cross-coupling reactions

4-Bromo-2,3,5-trichloro-6-iodopyridine was studied as a new substrate in chemoselective Sonogashira reactions. This approach provides an efficient access to non-symmetrical mono-, di-, tri- and pentaalkynylated pyridines in good yields. Selected pentaalkynylated pyridines were studied with regard to their UV/Vis- and emission properties showing moderate to high fluorescence quantum yields.