Cross-coupling Reactions Of Aryl Research Articles

Stille-type aryl–aryl cross-coupling catalysis using triarylphosphine ligands with electron-rich Fe(ii)-alkynyl substituents

The synthesis of four new phosphane ligands featuring electron-rich Fe(II) “(η2-dppe)(η5-C5Me5)FeCC-” substituents in para and meta position(s) on the aryl rings (1–4) is reported along with those of the corresponding PdCl2(PAr3)2 precatalysts (7–10). These precatalysts have then been tested in a Stille-type aryl–aryl cross coupling reaction. It is shown that these new ligands survive the reaction conditions and perform at least as well as the classic triphenylphosphine ligand for this transformation.

ChemInform Abstract: Synthesis of Functionalized Organotin Compounds via Palladium- Catalyzed Cross-Coupling Reaction of Aryl or 1-Alkenyl Halides with 9-( ω-Stannylalkyl)-9-borabicyclo(3.3.1)nonanes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Microwave-assisted C-C cross-coupling reactions of aryl and heteroaryl halides in water

The catalytic activity of a benzimidazole-oxime Pd(II)-complex towards Suzuki and Heck C-C cross-coupling reactions of activated and deactivated aryl- and heteroaryl bromides under microwave irradiation as well as thermal heating using water as a green solvent was evaluated. The turnover frequency reached 420,000 under microwave condition.

ChemInform Abstract: Total Synthesis of Michellamines A-C, Korupensamines A-D, and Ancistrobrevine B.

Efficient syntheses of the title compounds have been developed. Several strategies for preparation of each of the naphthalene and tetrahydroisoquinoline (THIQ) portions were developed. Initial attempts to use benzyne plus furan cycloaddition reactions were thwarted by the unfavorable sense of the regiochemical outcome. An interesting annulation reaction of benzynes derived from 2,4-dibromophenol derivatives formed the core of the shortest naphthalene synthesis. An alternative annulation initiated by the addition of a benzylic sulfone anion to methyl crotonate led to an efficient naphthol synthesis amenable to large scale. The THIQ synthesis of Bringmann was used initially and subsequently complemented by a route whose key step involved the opening of N-tosyl-2-methylethyleneimine by a 3,5-dimethoxyphenylcuprate reagent. The results from a variety of aryl cross-coupling reactions are described. Suzuki coupling of the boronic acid derived from the naphthalene moiety with a THIQ-iodide was the most generally...

Heck and Suzuki cross-couplings of aryl and heteroaryl bromides in water using a new palladium(II)-complex

A new benzimidazole-based Pd(II)-complex was prepared and its catalytic activity was evaluated in Heck and Suzuki C-C cross-coupling reactions of aryl and heteroaryl bromides with olefins and arylboronic acids, respectively, under thermal heating using water as a reaction solvent. The factors affecting the optimization of such reactions are studied.

Pd-catalyzed Dithiolene–Aryl Cross-coupling Reaction of Aromatic Cyclopentadienylcobalt Dithiolene Complex

Abstract [CpCo(dithiolene)] complex with a boronate group, which is formulated as [CpCo{S2C2(Ph)(Bpin)}] (1, Bpin = 4,4,5,5-tetramethyl-1,3,2-dioxaboronate), was prepared from the one-pot reaction of [CpCo(CO)2], elemental sulfur, and boronated alkyne. 1 underwent Pd-catalyzed Suzuki–Miyaura cross-coupling reactions with 3-bromopyridine or 9-bromoanthracene.

Preparation of Functionalized Aryl Iron(II) Compounds and a Nickel‐Catalyzed Cross‐Coupling with Alkyl Halides

The ortho-ferration of functionalized arenes using tmp2Fe⋅2 MgCl2⋅4 LiCl furnishes the corresponding diorgano FeII reagents at 25 °C in high yields. These reagents undergo cross-coupling reactions in the presence of 4-fluorostyrene to give various alkylated arenes. It turned out that NiII impurities present in commercial FeCl2 (98 % pure) catalyzed this alkyl–aryl cross-coupling reaction.

ChemInform Abstract: The Use of a Bifunctional Copper Catalyst in the Cross‐Coupling Reactions of Aryl and Heteroaryl Halides with Terminal Alkynes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Cross-Coupling Reactions of Aryl Pivalates with Boronic Acids

The first cross-coupling of acylated phenol derivatives has been achieved. In the presence of an air-stable Ni(II) complex, readily accessible aryl pivalates participate in the Suzuki-Miyaura coupling with arylboronic acids. The process is tolerant of considerable variation in each of the cross-coupling components. In addition, a one-pot acylation/cross-coupling sequence has been developed. The potential to utilize an aryl pivalate as a directing group has also been demonstrated, along with the ability to sequentially cross-couple an aryl bromide followed by an aryl pivalate, using palladium and nickel catalysis, respectively.

Palladium−Phosphinous Acid-Catalyzed Cross-Coupling of Aryl and Acyl Halides with Aryl-, Alkyl-, and Vinylzinc Reagents

Several palladium-phosphinous acids have been prepared and employed in cross-coupling reactions of aryl or acyl halides with aliphatic and aromatic organozinc reagents. The POPd7-catalyzed reaction of aryl halides, including electron-rich aryl chlorides, and arylzinc reagents was found to afford biaryls exhibiting alkoxy, alkylthio, amino, ketone, cyano, nitro, ester, and heteroaryl groups in 75-93% yield. Excellent results were obtained with sterically hindered substrates which gave di- and tri -ortho-substituted biaryls in up to 92% yield. Aryl halides also undergo POPd7-catalyzed aryl-vinyl and aryl-alkyl bond formation under mild conditions. Styrenes and alkylarenes were prepared in 79-93% yield from aryl halides and vinyl or alkylzinc reagents. The replacement of aryl halides by acyl halides provides access to ketones which were produced in up to 98% yield when POPd was used as catalyst. This approach overcomes the limited substrate scope, reduced regiocontrol, and low functional group tolerance of traditional Friedel-Crafts acylation methods.

Preparation, Structure, and Reactivity of Nonstabilized Organoiron Compounds. Implications for Iron-Catalyzed Cross Coupling Reactions

A series of unprecedented organoiron complexes of the formal oxidation states -2, 0, +1, +2, and +3 is presented, which are largely devoid of stabilizing ligands and, in part, also electronically unsaturated (14-, 16-, 17- and 18-electron counts). Specifically, it is shown that nucleophiles unable to undergo beta-hydride elimination, such as MeLi, PhLi, or PhMgBr, rapidly reduce Fe(3+) to Fe(2+) and then exhaustively alkylate the metal center. The resulting homoleptic organoferrate complexes [(Me 4Fe)(MeLi)][Li(OEt 2)] 2 ( 3) and [Ph 4Fe][Li(Et 2O) 2][Li(1,4-dioxane)] ( 5) could be characterized by X-ray crystal structure analysis. However, these exceptionally sensitive compounds turned out to be only moderately nucleophilic, transferring their organic ligands to activated electrophiles only, while being unable to alkylate (hetero)aryl halides unless they are very electron deficient. In striking contrast, Grignard reagents bearing alkyl residues amenable to beta-hydride elimination reduce FeX n ( n = 2, 3) to clusters of the formal composition [Fe(MgX) 2] n . The behavior of these intermetallic species can be emulated by structurally well-defined lithium ferrate complexes of the type [Fe(C 2H 4) 4][Li(tmeda)] 2 ( 8), [Fe(cod) 2][Li(dme)] 2 ( 9), [CpFe(C 2H 4) 2][Li(tmeda)] ( 7), [CpFe(cod)][Li(dme)] ( 11), or [Cp*Fe(C 2H 4) 2][Li(tmeda)] ( 14). Such electron-rich complexes, which are distinguished by short intermetallic Fe-Li bonds, were shown to react with aryl chlorides and allyl halides; the structures and reactivity patterns of the resulting organoiron compounds provide first insights into the elementary steps of low valent iron-catalyzed cross coupling reactions of aryl, alkyl, allyl, benzyl, and propargyl halides with organomagnesium reagents. However, the acquired data suggest that such C-C bond formations can occur, a priori, along different catalytic cycles shuttling between metal centers of the formal oxidation states Fe(+1)/Fe(+3), Fe(0)/Fe(+2), and Fe(-2)/Fe(0). Since these different manifolds are likely interconnected, an unambiguous decision as to which redox cycle dominates in solution remains difficult, even though iron complexes of the lowest accessible formal oxidation states promote the reactions most effectively.

Palladium‐Catalyzed N‐Arylation Reactions with Aziridine and Azetidine.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Iron-catalyzed aryl–aryl cross-coupling reaction tolerating amides and unprotected quinolinones

The iron(III)-catalyzed cross-coupling reaction between functionalized arylcopper reagents and aromatic iodides bearing an amide function or an unprotected quinolinone leads smoothly to polyfunctionalized biphenyls in excellent yields due to an intramolecular chelating effect of the amide group.

Combining enabling techniques in organic synthesis: solid-phase-assisted catalysis under microwave conditions using a stable Pd(II)-precatalyst

The catalytic activity of a 2-pyridinealdoxime-based Pd(II)-complex covalently anchored via the oxime moiety to a glass/polymer composite material was evaluated in Suzuki–Miyaura cross-coupling reactions of aryl and heteroaryl halides, including arylchlorides, with aryl and heteroaryl boronic acids both under thermal as well as microwave irradiating conditions in water. The stability and reusability of this Pd-precatalyst is part of the present study.

A Highly Effective (Triphenyl phosphite)palladium Catalyst for a Cross—Coupling Reaction of Allylic Alcohols with Organoboronic Acids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

An exploration of Suzuki aryl cross coupling chemistry involving [2.2]paracyclophane derivatives

Suzuki aryl cross coupling reactions using derivatives of [2.2]paracyclophane were examined. A variety of aryl boronic acids and pinacolate esters were successfully cross coupled with 4-bromo[2.2]paracyclophane under standard Suzuki conditions. Whilst an excellent tolerance for electron donating and withdrawing groups was observed, cross coupling reactions with highly sterically demanding borates (e.g. mesityl) were unsuccessful. The preparation and stability of the previously unreported [2.2]paracyclophanyl-4-boronic acid, -pinacolate ester and -dimethyl ester are described, along with the utility of these systems in Suzuki aryl cross coupling reactions. Application of this methodology led to a dicyclophane containing two [2.2]paracyclophane units separated by a 4-4' connected biphenyl spacer group.

Suzuki aryl cross-coupling chemistry using derivatives of 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane

An exploration into the scope of Suzuki aryl cross-coupling chemistry using derivatives of 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane is reported. The coupling of 4-iodo-1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane with various aryl boronic acids and boronic acid pinacol esters was successful, with the exception of very sterically demanding systems, such as mesityl. The synthesis of the previously unreported 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophanyl-4-boronic acid is described, together with various Suzuki aryl cross-coupling reactions of this new system. Using standard Suzuki methodology, it was possible to prepare dicyclophanes bearing two octafluoro[2.2]paracyclophane units separated by both one and two benzene rings.

A Highly Effective (Triphenyl phosphite)palladium Catalyst for a Cross−Coupling Reaction of Allylic Alcohols with Organoboronic Acids

AbstractThe cross coupling reaction of aryl and vinyl boronic acids and allylic alcohols proceeded smoothly in toluene or dioxane in the presence of a (triphenyl phosphite)palladium catalyst to give the corresponding allylbenzene derivatives and 1,4‐dienes. Neither cocatalysts for promoting C−O bond cleavage of allylic alcohols nor bases for activation of organoboron reagents are required for promoting the coupling process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Catalysis-based enantioselective total synthesis of the macrocyclic spermidine alkaloid isooncinotine

A concise and efficient total synthesis of the spermidine alkaloid (-)-isooncinotine (1) incorporating a 22-membered lactam ring is outlined. The approach is largely catalysis-based, involving a selective iron-catalyzed alkyl-aryl cross-coupling reaction of a difunctionalized pyridine substrate, a heterogeneous asymmetric hydrogenation step to set the chiral center of the target, and a highly integrated ring-closing metathesis/hydrogenation sequence to forge the saturated macrocyclic edifice in a single operation.

The Synthesis of OSU 6162: Efficient, Large-Scale Implementation of a Suzuki Coupling

The synthesis of the chiral, nonracemic 3-aryl piperidine, OSU 6162 (1), a potential CNS agent from Pharmacia Corporation, is presented. The key construction in the described synthesis is a palladium-catalyzed aryl cross-coupling reaction between bromosulfone (4) and pyridyl borane (14). Initially developed conditions for this Suzuki reaction, conducted in tetrahydrofuran/aqueous hydroxide, delivered free base (6) or hydrochloride salt (15a) in reproducible 80% yield. However, by changing the solvent to toluene and the base to carbonate, significant decreases in catalyst requirement were realized, and the methane sulfonate salt (15b) of the coupled product could be obtained in reproducible 92−94% yield on 200-kg input. The success of the Suzuki reaction was critically dependent on a bulk source of the pyridyl borane coupling partner. Cryogenic conditions were developed for its generation via lithium−halogen exchange to generate thermally labile 3-lithiopyridine followed by transmetalation with diethylmeth...