2-Aryl propionamides via 1,4-aryl radical migration from N-arylsulfonyl-2-bromopropionamides

Reaction of N-alkyl-N-arylsulfonyl-2-halo-propionamides with pentamethyldiethylenetriamine and either CuBr or CuCl leads to 2-aryl propionamides via initial radical generation, 1,4-aryl migration with loss of SO₂ and reduction of the intermediate amidyl radical in 40-99% yields.     

Copper mediated atom transfer radical cyclisations with AIBN

We have shown that it is possible to mediate a range of 5-exo trig and 5-exo dig atom transfer radical cyclisations of bromoacetamides using 0.1-1 mol % CuBr or CuBr₂ in conjunction with 0.1-1 mol % tri(pyridin-2-ylmethyl)amine and 10 mol % AIBN. This equates to a 30-300-fold reduction in the amount of catalyst previously reported for these reactions and allows cyclisation to be carried out with the more oxidatively stable CuBr₂ without the requirement of an inert atmosphere.     

Atom transfer radical cyclization reactions (ATRC): synthetic applications

Atom transfer cyclization reactions (ATRC) provide rapid access to functionalized γ-butyrolactones.     

New reactivity patterns of copper(I) and other transition metal NHC complexes: application to ATRC and related reactions

Pre-formed transition metal-NHC complex is shown to be an effective catalyst for Atom Transfer Radical Cyclisation (ATRC) reactions.     

Bis(μ-iodo)bis((−)-sparteine)dicopper(I) catalyzed Sonogashira-type reaction under palladium and phosphine-free conditions

An efficient and inexpensive protocol for the Sonogashira-type cross coupling reactions of phenylacetylenes with a variety of haloarenes including activated aryl chlorides employing the structurally well-characterized bis(μ-iodo)bis((−)-sparteine)dicopper(I) catalyst is described.     

Reverse atom transfer radical polymerisation (RATRP) of methacrylates using copper(I)/pyridinimine catalysts in conjunction with AIBN

N-n-Propyl-2-pyridylmethanimine, 1, N-n-octyl-2-pyridylmethanimine, 2, N-n-lauryl-2-pyridylmethanimine, 3, and N-n-octadecyl-2-pyridylmethanimine, 4 have been used in conjunction with copper(II) bromide and azo initiators for the reverse atom transfer radical polymerisation of a range of methacrylates. AIBN to Cu^IIBr₂ ratios of 0.5:1, 0.75:1 and 1:1 give PMMA with M_n 11 500 g mol⁻¹ (PDi = 1.24) (at 22% conversion), 12 500 g mol⁻¹ (PDi = 1.06) (at 83% conversion) and 10 900 g mol⁻¹ (PDi = 1.11) (at 84% conversion), respectively. A Cu^IIBr₂ complex is demonstrated to be needed at the start of the reaction for good control over molecular weight and polydispersity as reactions using Cu(I)Br as catalyst yielded PMMA of M_n 31 000 g mol⁻¹ (PDi = 2.90), reactions with no copper yield PMMA of M_n 33 000 g mol⁻¹ (PDi = 2.95). The RATRP of styrene was carried out using Cu^IIBr₂ as catalyst. AIBN to Cu^IIBr₂ ratio of 0.5:1, 0.75:1 and 1:1 gave PS with M_n = 12 400 g mol⁻¹ (PDi = 1.27) at low conversion, M_n = 15 500 g mol⁻¹ (PDi = 1.11) and 12 400 g mol⁻¹ (PDi = 1.38), respectively at ∼85% conversion. A series of block copolymers of MMA with BMA, BzMA and DMEAMA (15 600 g mol⁻¹ (PDi = 1.18), 13 300 g mol⁻¹ (PDi = 1.14) 15 300 g mol⁻¹ (PDi) = 1.16), using a PMMA macroinitiator were prepared. Emulsion polymerisation of MMA using [initiator]:[Cu^(II)Br₂] ratio = 0.5:1 with Brij surfactant gave a linear increase of M_n with respect to conversion, final M_n = 112 800 g mol⁻¹ (PDi = 1.42). Further reactions were carried out with [initiator]:[Cu^(II)Br₂] ratio = 0.75:1 and 1:1. Both giving PMMA with M_n ∼ 32 000 g mol⁻¹ (PDi ∼ 2.4). These reactions exhibit no control, this is because the azo initiator is present in excess and all of the monomer is consumed by a free radical polymerisation as opposed to a controlled reaction. Particle size analysis (DLS) showed the particle size between 160 and170 nm in all cases.     

Ligand free open air copper(II) mediated aryl formamidation and amination of aryl halides

A simple synthetic procedure for direct formamidation and amination of aryl halides mediated by copper(II) salts was developed in open air, without an external ligand in formamide with potassium carbonate as a base. This approach is particularly efficient when electron active aryl halides are used as substrates. In these cases almost quantitative formamidation was observed.     

Coupled atom transfer radical coupling and atom transfer radical polymerization approach for controlled grafting from poly(vinylidene fluoride) backbone

A new “grafting from” strategy for grafting of different monomers (methacrylates, acrylates, and acrylamide) on poly(vinylidene fluoride) (PVDF) backbone is designed using atom transfer radical coupling (ATRC) and atom transfer radical polymerization (ATRP). 4‐Hydroxy TEMPO moieties are anchored on PVDF backbone by ATRC followed by attachment of ATRP initiating sites chosen according to the reactivity of different monomers. High graft conversion is achieved and grafting of poly(methyl methacrylate) (PMMA) exhibits high degree of polymerization (DPn = 770) with a very low graft density (0.18 per hundred VDF units) which has been increased to 0.44 by regenerating the active catalyst with the addition of Cu(0). A significant impact on thermal and stress–strain property of graft copolymers on the graft density and graft length is noted. Higher tensile strain and toughness are observed for PVDF‐g‐PMMA produced from model initiator but graft copolymer from pure PVDF exhibits higher tensile strength and Young's modulus. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 995–1008     

Carbocyanation of trisubstituted olefins via Cu-catalyzed atom transfer radical addition

A regioselective Cu(I)-catalyzed carbocyanation of non-polarized trisubstituted olefins 1 has been achieved by employing chlorinated cyanides 2 as starting materials. The present reaction gives the carbocyanated product 3 through radical-based 1,3-transfer of CN. Consequently, two different carbon units, cyano and chlorocyanomethyl groups, are introduced into the highly substituted olefins, generating consecutive quaternary and tertiary carbons. Since both of the attached carbon units can be used as handles for further synthetic elaborations, the present transformation offers a new synthetic methodology for rapid construction of architecturally complex carboskeletons.     

Novel polymers from atom transfer polymerisation mediated by copper(I) Schiff base complexes

The use of copper(I) Schiff base complex catalysed atom transfer polymerisation of methacrylates is described. The use of a range of functional and multi‐functional initiators enables the synthesis of a range of functional and star polymers to be prepared under undemanding synthetic conditions. End capping with silyl enol ethers allows for ω‐functional polymers. The combination of novel initiators, functional monomers and end capping allows an unprecedented array of macromolecular structures to be produced with limited need for protecting group chemistry.     

可循环疏水性铜酞菁催化咪唑的N-芳基化反应

研究了二价铜酞菁(CuPc)催化咪唑与芳基碘或溴的N-芳基化反应.结果表明,CuPc表现出高的催化活性,并且能够重复使用3次活性无明显降低.采用傅里叶变换红外光谱、X射线光电子能谱和紫外-可见光谱对催化剂样品进行了表征.     

Virus-glycopolymer conjugates by copper(I) catalysis of atom transfer radical polymerization and azide-alkyne cycloaddition

The Cu(I)-catalyzed ATRP and azide-alkyne cycloaddition reactions together provide a versatile method for the synthesis of end-functionalized glycopolymers and their attachment to a suitably modified viral protein scaffold.     

Photoluminescence studies of iodobis-(tricyclohexylphosphine)copper(I) and iodobis-(tricyclohexylphosphine)copper(I) benzene solvate

Two newly prepared complexes were found to exhibit strong solid state emission behavior. The complexes are iodobis-(tricyclohexylphosphine)copper(I) and iodobis-(tricyclohexylphosphine)copper(I) benzene solvate. To understand the emission behavior of these complexes, density functional theory (DFT) calculations were employed. These calculations allowed the identification of major atomic contributions to HOMO, LUMO and LUMO+n orbitals. The excitation mechanism was found to be a combination of ligand to metal charge transfer (LMCT) and metal to ligand charge transfer (MLCT), with the dominance of the former. The emission lifetimes were also investigated and the decays of the complexes were found to be a bi-exponential in both methanol and cyclohexane.     

Systematic investigations of the multi-element preconcentration from copper by precipitation of the matrix as copper(I) oxide and copper(I) thiocyanate

Two methods for multi-element preconcentration from copper by reductive matrix precipitation are presented. In systematic investigations on the coprecipitation behaviour of Ag, Al, Au, Bi, Cd, Co, Cr, Fe, Ga, In, Mn, Mo, NJ, Pb, Sb, Se, Sn, Te and Zn during precipitation of the copper matrix as Cu₂O or CuSCN, the separation parameters were optimized. By combination with a hexamethyleneammonium hexamethylenedithiocarbamate collector precipitation, a concentration of 8 elements (Cu₂O precipitation) or 13 elements (CuSCN precipitation) in a small volume was achieved. The limits of detection of the procedures are, depending on the element, 0.1–5 μg g^?1 for flame atomic absorption spectrometry (AAS) and 0.01–0.1 μg g^?1 for graphite furnace AAS. The relative standard deviations are about 3%. The analytical performance of the procedures is compared with that of an electrolytic copper separation.     

Short and convenient synthesis of two natural phthalides by a copper(I) catalysed Sonogashira/oxacyclisation copper(I) process

Total synthesis of (±)-herbaric acid and (±)-(4-methoxybenzyl)-5,7-dimethoxyphthalide, two natural phthalide products, was achieved in 8 steps and 5 steps, respectively, starting from commercially available 3,5-dimethoxyaniline. The key step of the sequence included a copper-catalysed tandem cross-coupling and oxacylisation reaction of terminal alkynes and 2-iodobenzoïc acid derivatives via 5-exo-dig cyclisation with high stereo-, regio- and chemoselectivities. This straightforward method allows the preparation of diverse phthalides, which belong to a group of pharmacologically important compounds.     

Rapid and mild synthesis of quinazolinones and chromeno[d]pyrimidinones using nanocrystalline copper(I) iodide under solvent-free conditions

This paper describes a very simple, efficient synthesis of quinazolinones and chromeno[d]pyrimidinones from the reaction of aryl aldehydes, urea/thiourea and active methylene compounds(dimedone/4-hydroxycoumarin) using nano-sized CuI particles under solvent-free conditions. The highlights of this new method are based on using an effective and recyclable catalyst, affording high yields of products, mild reaction conditions, facile work-up and purification.     

Copper(I) thiophenolate in copper N-heterocyclic carbene preparation

Copper(I) thiophenolate was considered as a copper source for the synthesis of Cu(I)-N-heterocyclic carbenes (Cu(I)-NHCs). It displayed a dual mode of reactivity allowing the synthesis of both thiophenolato-Cu(I)-NHCs via the free carbene in a one-pot procedure starting from imidazolium chlorides and chloro-Cu(I)-NHCs by a salt metathesis reaction starting from chloro-Ag(I)-NHCs.     

Reaction of aryl azides with tris(trimethylsilyl)silyllithium: Synthesis of tmeda or thf adducts of [Li{N(Ar)Si(SiMe3)3}] and 1,4-trimethylsilyl migration from oxygen to nitrogen

Reaction of ArN₃ (Ar = Ph, p-MeC₆H₄, 1-naphthyl) with [Li{Si(SiMe₃)₃}(thf)₃] yielded lithium amides [Li{N(Ar)Si(SiMe₃)₃}L] (L = tmeda or (thf)₂). Similar treatment of o-phenylene diazide with 2 equiv. of [Li{Si(SiMe₃)₃}(thf)₃] formed dilithium diamide complex 4. Reaction between o-Me₃SiOC₆H₄N₃ and [Li{Si(SiMe₃)₃}(thf)₃] afforded, via 1,4-trimethylsilyl migration from oxygen to nitrogen, [Li{OC₆H₄{N(SiMe₃)Si(SiMe₃)₃}-2}]₂ (5). The structures of complexes 3 and 5 have been determined by single crystal X-ray diffraction techniques.     

Synthesis of N,O-heterocyclic carbene and coordination to rhodium(I) and copper(I)

5,7-Di-tert-butyl-3-phenyl benzoxazolium tetrafluoroborate 1 could be prepared by simple reaction of the corresponding aminophenol with triethyl orthoformate under acidic conditions. Both rhodium(I) and copper(I) complexes with benzoxazol-2-ylidene ligand were then efficiently synthesised in a straightforward and smooth manner involving the reaction of benzoxazolium salt 1 with metal precursor and an external base. The complexes have been fully characterised and used in metal-catalysed hydrosilylation of ketones, where they showed poor catalytic activity, presumably due to low stability of the complexes under those conditions.     

Identification and characterization of monoanionic tripodal tetradentate ligand complexes of copper(I) and copper(II) involved in halogen atom transfer reactions

The copper(I) complex of bis-(2-(2-pyridyl)-ethyl)-(2-(N-p-toluenesulfonamido)-ethyl)amine (PETAEA), a monoanionic, tripodal tetradentate ligand, was prepared, characterized, and shown to be an effective catalyst for atom transfer radical polymerization (ATRP). A model atom transfer reaction of Cu(PETAEA) with 1-phenylethyl bromide and TEMPO radical trapping agent was studied. The copper(II) complex formed in this reaction was identified by comparison of its spectroscopic data with that of Cu(PETAEA)Br prepared by an independent synthesis. Kinetic and spectroscopic data indicated that the reaction mechanism involved simple atom transfer from the alkyl halide to the Cu(PETAEA) to form the Cu(PETAEA)Br, and no other intermediates were involved. The solid-state structures of the copper(I) and (II) complexes appeared to be maintained in solution, so this system is an atom transfer reaction in which all of the reactive species are identified and characterized.