Reactivity of mixed organozinc and mixed organocopper reagents: 6. Nickel-catalyzed coupling of methylarylzincs with primary alkyl halides; an atom-economic aryl-alkyl coupling

A nickel-catalyzed process for the cross-coupling of mixed arylzincs and primary alkyl halides has been developed. The reaction of a methylarylzinc with a primary alkyl halide in THF in the presence of NiCl₂/PPh₃ takes place with selective aryl transfer at room temperature in moderate yields. This protocol provides an atom-economic alternative to aryl-primary alkyl coupling using diarylzincs.     

Reactivity of mixed organozinc and organocopper reagents. 3. Atom economic electrophilic amination of methyl arylzinc reagents

Reaction of methyl arylzincs with acetone O‐(mesitylenesulfonyl)oxime in THF in the presence of CuCN at room temperature is efficient in selective electrophilic amination of aryl carbanions. This procedure allows for the preparation of arylamines in moderate to good yields and provides an efficient and atom economic alternative to existing amination methods for diarylzincs. Copyright © 2009 John Wiley & Sons, Ltd.     

Reactivities of mixed organozinc and mixed organocopper reagents, 2. Selective n-alkyl transfer in tri-n-butylphosphine-catalyzed acylation of n-alkyl phenylzincs; an atom economic synthesis of n-alkyl aryl ketones

Tri-n-butylphosphine-catalyzed acylation of mixed n-alkyl phenylzincs with aromatic acyl halides in THF is efficient in selective transfer of n-alkyl groups to produce n-alkyl aryl ketones in good yields. This route provides an atom economic organocatalyzed alternative to transition metal-catalyzed acylation of di-n-alkylzincs.     

Iron‐catalyzed cross‐coupling of heteroaromatic tosylates with alkyl and aryl Grignard reagents

An Fe(III)‐catalyzed cross‐coupling of N‐heteroaromatic tosylates with aryl and alkyl Grignard reagents is presented. The reaction proceeds at ?20°C to room temperature with short reaction time (15–30 min.), and the corresponding products are obtained with moderate to high yields. In particular, low‐cost and abundantly available FeCl₃ or Fe(acetylacetonate)₃ catalyze the reaction without other special ligands. All tested N‐heteroaromatic tosylates that are available including pyridine and pyrimidine derivatives were subject to the reaction, resulting in the expected products. Copyright © 2015 John Wiley & Sons, Ltd.     

Suzuki–Miyaura coupling reactions of aryl chlorides catalyzed by a new nickel(II) σ‐aryl complex

A new nickel(II) σ‐aryl complex, trans‐chloro(9‐phenanthrenyl)bis(triphenylphosphine)nickel(II), was used as a precatalyst for the Suzuki–Miyaura coupling reactions of aryl chlorides. The catalytic conditions were optimized by investigating the cross‐coupling of p‐chloroanisole with phenylboronic acid. The results show that this complex is efficient for both electron‐rich and electron‐deficient aryl chlorides, though it gives better yields for activated arylboronic acids than deactivated ones. All isolated cross‐coupled biaryl products have been characterized by ¹H and ¹³C NMR, and their spectral data are consistent with those reported. Side products from the coupling of arylboronic acid with the precatalyst complex have also been isolated and characterized, which is helpful for understanding the coupling mechanism. Copyright © 2013 John Wiley & Sons, Ltd.     

Pd(0)‐catalyzed polycondensation of aryl‐substituted propargylic carbonates with bifunctional nucleophiles promoted by aryl group on the acetylenic terminal carbon

A Pd(0)‐catalyzed polycondensation of bifunctional nucleophiles and propargylic carbonates having an aryl group was investigated. The polycondensation was carried out for tetrahydrofuran at 60 °C for 3 h in the presence of Pd(0) catalyst. The Pd(0)‐catalyzed polycondensation of phenyl‐substituted propargylic carbonates and nucleophiles proceeded efficiently, when bis[(2‐diphenylphosphino)phenyl]ether was used as the ligand. We found that the position of the phenyl group was crucial for the successful polycondensation. The introduction of a phenyl group on the acetylenic terminal carbon remarkably promoted the polycondensation and afforded high molecular weight polymers. On the other hand, a phenyl group at the propargylic position was not effective. Propargylic carbonates having a substituted phenyl group were also examined. Electron‐withdrawing group‐substituted phenyl groups on the acetylenic terminal carbon were found to be more effective for the polycondensation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Nickel‐catalyzed Buchwald–Hartwig amination of pyrimidin‐2‐yl tosylates with indole,benzimidazole and 1,2,4‐triazole

Nickel‐catalyzed Buchwald–Hartwig amination of pyrimidin‐2‐yl tosylates with indole and benzimidazole was achieved using Ni(dppp)Cl₂ as catalyst, yielding a variety of novel C2‐substituted pyrimidine derivatives in good yields. This reaction proved to be tolerant of various pyrimidin‐2‐yl tosylates bearing either electron‐donating or electron‐withdrawing groups as well as nucleophiles including indole, benzimidazole and 1,2,4‐triazole. Copyright © 2016 John Wiley & Sons, Ltd.     

An efficient heterogeneous cross‐coupling of aryl iodides with diphenylphosphine catalyzed by copper (I) immobilized in MCM‐41

The heterogeneous cross‐coupling reaction of aryl iodides with diphenylphosphine was achieved in toluene at 115 °C in the presence of 10 mol% of phenanthroline‐functionalized MCM‐41‐supported copper (I) complex (Phen‐MCM‐41‐CuI) with Cs₂CO₃ as base, yielding various unsymmetric triarylphosphines in good to excellent yields. This protocol can tolerate a wide range of functional groups and does not need the use of expensive additives or harsh reaction conditions. This heterogeneous Cu (I) catalyst exhibited the same catalytic activity as homogeneous CuI/Phen system, and could easily be recovered by a simple filtration of the reaction solution and recycled up to seven times without significant loss of activity.     

Nickel‐catalyzed aminocarbonylation of aryl halides with carbamoylsilanes: efficient synthesis of secondary (primary) aromatic amides

A nickel‐catalyzed aminocarbonylation of aryl halides using carbamoylsilane as an amide source leading to corresponding secondary or primary aromatic amides has been developed, in which the methoxymethyl and benzyl were used as amino protecting group. The protocol tolerates a broad range of aryl halides bearing different functional groups to afford good yields of aryl amides under mild reaction conditions. The types and the relative positions of substituents on the aryl ring make a notable impact on the coupling efficiency. The plausible mechanism of nickel‐catalyzed aminocarbonylation has been suggested.     

The first heterogeneous Sonogashira coupling reaction of aryl halides with terminal alkynes catalyzed by diatomite‐supported palladium(II) salophen complex

We report here our observation that, using appropriate reaction conditions, the Sonogashira reaction can be performed without the need for copper catalyst and solvent. Our approach involves the use of diatomite‐supported palladium(II) salophen complex as a catalyst and triethylamine as a base. The methodology works, to differing extents, for aryl iodides and bromides. This heterogeneous catalyst can be reused at least five times without any decrease in activity. Copyright © 2011 John Wiley & Sons, Ltd.     

Polymerization of 1,3‐dienes and styrene catalyzed by cationic allyl Ni(II) complexes

Polymerizations of 1,3‐dienes using in situ generated catalyst [(2‐methallyl)Ni][B(Ar_F)₄], 6 , (Ar_F = 3,5‐bis(trifluoromethyl)phenyl) as well as [(2‐methallyl)Ni(mes)][B(Ar_F)₄], 14 , (mes = mesitylene) are reported. Highly sensitive complex 6 polymerizes butadiene (BD) at –30 °C to yield polybutadiene with a M_n of ca. 10 K and 94% cis‐1,4‐enchainment while less reactive isoprene (IP) was polymerized at 23 °C to yield polyisoprene with M_n ca. 7 K. Complex 6 was also shown to polymerize a functionalized diene, 2,3‐bis(4‐trifluoroethoxy‐4‐oxobutyl)‐1,3‐BD, to polymer with M_n = 113 K. The stable and readily isolated arene complex 14 initiates BD and IP polymerizations at somewhat higher temperatures relative to 6 and delivers polymers with higher molecular weights. Complex [(allyl)Ni(mes)][B(Ar_F)₄], 13 , catalyzes polymerization of styrene to yield polystyrene with high conversion, M_n's = ca. 6 K and MWD = 2. The π‐benzyl complex [(η³‐1‐methylbenzyl)Ni(mes)] [B(Ar_F)₄], 19 , was detected as an intermediate following chain transfer by in situ NMR studies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1901–1912, 2010     

Introduction of (2‐CF3)Phenyl Group via Nickel‐catalyzed C–Cl Bond Activation and Arylation

A simple and mild catalytic arylation via C–Cl bond activation is described. The phenyl group containing a 2‐trifluoromethyl group was introduced into the aromatic imine molecules through C,C‐coupling reaction between chloroarenes and the organozinc reagent, bis(2‐(trifluoromethyl)phenyl)zinc, with tetrakis(trimethylphosphine)nickel(0) complex as an effective catalyst. Under catalytic conditions chlorinated benzalimines were quantitatively converted into the expected benzalimines with trifluoromethyl group(s).     

Four-component coupling reactions of silylacetylenes, allyl carbonates, and trimethylsilyl azide catalyzed by a Pd(0)-Cu(I) bimetallic catalyst. Fully substituted triazole synthesis from seemingly internal alkynes

Fully substituted triazoles were synthesized via the four-component coupling reaction of unactivated silylacetylenes, two equivalents of allyl carbonates, and trimethylsilyl azide in the presence of a Pd(0)-Cu(I) bimetallic catalyst. Various trisubstituted 1,2,3-triazoles were obtained in good yields. The reaction most probably proceeds through the [3+2] cycloaddition reaction between the alkynylcopper species and azide followed by the cross-coupling reaction between the vinylcopper intermediate and π-allylpalladium complex.     

A highly efficient heterogeneous rhodium(I)‐catalyzed C–S coupling reaction of thiols with polychloroalkanes or alkyl halides under mild conditions

Heterogeneous C–S coupling reaction of thiols with polychloroalkanes or alkyl halides was achieved at 30 or 80 °C in the presence of 5 mol% of an MCM‐41‐immobilized bidentate phosphine rhodium complex (MCM‐41‐2P‐RhCl(PPh₃)) and triethylamine, yielding a variety of formaldehyde dithioacetals, ethylenedithioethers and unsymmetric thioethers in good to excellent yields. This heterogeneous rhodium catalyst can be easily recovered and recycled by simple filtration of the reaction solution and used for at least 10 consecutive trials without significant loss of activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Palladium‐catalyzed carbonylative cyclization of 1‐bromoallyl bromides with anilines leading to 1‐aryl‐1H‐pyrrol‐2(5H)‐ones

1‐Bromoallyl bromides are carbonylatively cyclized with anilines under carbon monoxide pressure in DMF in the presence of a catalytic amount of a palladium catalyst along with a base to give the corresponding 1‐aryl‐1H‐pyrrol‐2(5H)‐ones in moderate to good yield. Copyright © 2012 John Wiley & Sons, Ltd.     

Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide

Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide is described. In the reaction with allyl bromide, either a Pd(dba)₂? CuI combination (dba, dibenzylideneacetone) in DMF or copper(I) iodide in DMSO–THF readily catalyzes or mediates the coupling reaction of (Z)‐silyl(stannyl)ethenes at room temperature, producing novel vinylsilanes bearing an allyl group β to silicon with cis ‐disposition in good yields. Allyl chlorides as halides can be used in the CuI‐mediated reaction. CuI alone much more effectively mediates the cross‐coupling reaction with propargyl bromide in DMSO–THF at room temperature compared with a Pd(dba)₂? CuI combination catalysis in DMF, providing novel stereodefined vinylsilanes bearing an allenyl group β to silicon with cis ‐disposition in good yields. Copyright © 2008 John Wiley & Sons, Ltd.     

Investigation of Suzuki–Miyaura catalyst‐transfer polycondensation of AB‐type fluorene monomer using coordination‐saturated aryl Pd(II) halide complexes as initiators

Novel triarylamine‐based coordination‐saturated aryl Pd(II) halide complexes ligated by PEt₃, PCy₃, and P(o‐tol)₃ were successfully synthesized by direct oxidative addition of aryl halide to the corresponding Pd(0) precursors. Suzuki–Miyaura coupling polymerization of 2‐(7‐halide‐9,9‐dioctylfluoren‐2‐yl)?1,3,2‐dioxaborinane with these Pd(II) complexes as initiators was investigated for the synthesis of poly(fluorene)s with triarylamine end group. Pd(II) complexes with PCy₃ or P(o‐tol)₃ exhibited catalytic activity and realized the catalyst‐transfer polycondensation at 75 °C and room temperature, respectively, while the polymerization using Pd(II) catalyst ligated by PEt₃ did not proceed, which indicated that the bulky phosphine ligands could facilitate the reductive elimination and further promote the polymerization. In addition, the dimeric Pd(II) complex with P(o‐tol)₃ can convert into monomeric Pd(II) intermediate with an open coordination site, which had a higher activity. The end groups of the afforded polyfluorene were analyzed by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry, in which the Ar/H end groups are indicative of the catalyst‐transfer polymerization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1457–1463