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Palladium nanoparticles stabilised by aniline modified polymer immobilised ionic liquid is a remarkably active catalyst for the hydrogenation of CO2 to formate; the initial TOF of 500 h−1 is markedly higher than either unmodified catalyst or its benzylamine and N,N-dimethylaniline modified counterparts and is among the highest to be reported for a PdNP-based catalyst. [ABSTRACT FROM AUTHOR]

RuNPs stabilised by amino‐decorated imidazolium‐based polymer immobilized ionic liquids catalyse the dimethylamine borane mediated reduction of quinolines to 1,2‐dihydroquinoline (DHQ) and 1,2,3,4‐tetrahydroquinoline (THQ). Partial reduction of 3‐substituted quinolines to the corresponding 1,2‐dihydroquinoline was achieved with 100 % selectivity in toluene under mild conditions. This is the first report of the selective partial reduction of 3‐substituted quinolines to the corresponding 1,2‐dihydroquinolines with a heterogeneous nanoparticle‐based catalyst. A wide range of substituted quinolines have also been reduced to the corresponding 1,2,3,4‐tetrahydroquinoline with high selectivity and good yields by adjusting the reaction time. The 1,2‐dihydroquinolines readily release dihydrogen in toluene at 60 °C in the absence of catalyst with no evidence for disproportionation and as such are potential organo‐hydride reagents. The initial TOF of 610 mol quinoline converted mol Ru−1 h−1 for the reduction of quinoline is among the highest to be reported for a metal nanoparticle‐based catalyst and the conversion of 96 % obtained after 4 h at 65 °C is significantly higher than its platinum nanoparticle counterpart PtNP@NH2‐PEGPIILS as well as 5 wt/% Ru/C, which only reached 9 % and 11 % conversion, respectively, at the same time. Hot filtration experiments showed that the active species was heterogeneous. [ABSTRACT FROM AUTHOR]

Bimetallic Ru:Co nanoparticles stabilized by PEG and imidazolium ionic liquid based [KIT-6] mesoporous silica, denoted as Ru:Co NPs@[KIT-6]-PEG&imid 6, has been synthetized by post grafting method and fully characterized by SEM, TEM, XPS, FT-IR and solid-state 13C and 29Si NMR spectroscopy. The supported Ru:Co mesoporous nanoparticles catalyst 6 revealed excellent catalytic activity (conversions up to 100%), turnover number (TON) of 770 and turnover frequency (TOF) of 7700 h−1 in the Suzuki–Miyaura cross-coupling of p-bromobenzonitrile and phenylboronic acid in H2O:EtOH (1:1) solution under very mild reaction conditions. In addition, the heterogeneous catalyst 6 maintains almost its inherent catalytic activity after the 6th catalytic recycle. [ABSTRACT FROM AUTHOR]

Synthetically straightforward π‐extension of helically chiral N,N,O,O‐boron chelated borondipyrromethenes (BODIPYs) has been achieved by incorporation of naphthyl rings into the BODIPY 3‐ and 5‐positions. The effect of this extension on the photophysical and chiroptical properties is strongly dependent on the regiochemistry of the naphthyl substituents (4 exo, 4 lin, 4 endo). The most helicene‐like regioisomer 4 endo is a near infra‐red (NIR) emitter (λemmax=751 nm) with an emission band between 675–875 nm, displaying circularly polarised luminescence (CPL) with a luminescence dissymmetry factor, |glum|=5.7×10−3 and CPL brightness, BCPL=27, rivalling the best NIR CPL‐emitting small organic molecules reported to date. [ABSTRACT FROM AUTHOR]

A comparative study of the carbonyl-ene reaction between a range of 1,1'-disubstituted or trisubstituted alkenes and ethyl trifluoropyruvate catalyzed by Lewis acid-platinum group metal complexes of the type [M{(R)-BINAP}].sub.2.plus (M= Pt, Pd, Ni; BINAP is 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl), is presented. The palladium-based Lewis acid [Pd-{(R)-BINAP}].sup.2.plus is found to catalyze the ene reaction between methylene cycloalkane to afford the expected [alpha]-hydroxy ester in good yield and excellent diastereo- and enantioselectivity.

Platinum nanoparticles stabilized by imidazolium‐based phosphine‐decorated Polymer Immobilized Ionic Liquids (PPh2‐PIIL) catalyze the hydrolytic evolution of hydrogen from sodium borohydride with remarkable efficiency, under mild conditions. The composition of the polymer influences efficiency with the catalyst based on a polyethylene glycol modified imidazolium monomer (PtNP@PPh2‐PEGPIILS) more active than its N‐alkylated counterpart (PtNP@PPh2‐N‐decylPIILS). The maximum initial TOF of 169 moleH2.molcat−1.min−1 obtained at 30 °C with a catalyst loading of 0.08 mol% is among the highest to be reported for the aqueous phase hydrolysis of sodium borohydride catalyzed by a PtNP‐based system. Kinetic studies revealed that the apparent activation energy (Ea) of 23.9 kJ mol−1 for the hydrolysis of NaBH4 catalyzed by PtNP@PPh2‐PEGPIILS is significantly lower than that of 35.6 kJ mol−1 for PtNP@PPh2‐N‐decylPIILS. Primary kinetic isotope effects kH/kD of 1.8 and 2.1 obtained with PtNP@PPh2‐PEGPIILS and PtNP@PPh2‐N‐decylPIILS, respectively, for the hydrolysis with D2O support a mechanism involving rate determining oxidative addition or σ‐bond metathesis of the O−H bond. Catalyst stability and reuse studies showed that PtNP@PPh2‐PEGPIILS retained 70 % of its activity across five runs; the gradual drop in conversion appears to be due to poisoning of the catalyst by the accumulated metaborate product as well as the increased viscosity of the reaction mixture. [ABSTRACT FROM AUTHOR]

A new family of boron(III) chelates is introduced whereby molecular chirality, confirmed by circular dichroism, is imported during synthesis such that isolation of the diastereoisomers does not require separation procedures. The photophysical properties of two members of the family have been examined: the N,O,O‐salicylaldehyde‐based derivative shows pronounced intramolecular charge‐transfer character in fluid solution and is weakly fluorescent, with a large Stokes shift. The corresponding 2‐methylamino‐benzaldehyde‐derived N,N,O‐chelate absorbs and fluoresces in the visible region with a much smaller Stokes shift. Orange fluorescence is also observed for this compound as a cast film. Temperature‐dependence studies show that decay of the fluorescent state is weakly activated but emission is less than quantitative at 77 K. Quite rare for boron(III)‐based chelates, this derivative undergoes intersystem crossing to form a meta‐stable triplet‐excited state. X‐ray crystal structures are reported for both compounds, along with simulated ECD spectra. [ABSTRACT FROM AUTHOR]

The Noyori‐Ikariya (arene)Ru(II)/TsDPEN precatalyst has been anchored to amorphous silica and DAVISIL through the η6‐coordinated arene ligand via a straightforward synthesis and the derived systems, (arene)Ru(II)/TsDPEN@silica and (arene)Ru(II)/TsDPEN@DAVISIL, form highly efficient catalysts for the asymmetric transfer hydrogenation of a range of electron‐rich and electron‐poor aromatic ketones, giving good conversion and excellent ee's under mild reaction conditions. Moreover, catalyst generated in situ immediately prior to addition of substrate and hydrogen donor, by reaction of silica‐supported [(arene)RuCl2]2 with (S,S)‐TsDPEN, was as efficient as that generated from its preformed counterpart [(arene)Ru{(S,S)‐TsDPEN}Cl]@silica. Gratifyingly, the initial TOFs (up to 1085 h−1) and ee's (96–97 %) obtained with these catalysts either rivalled or outperformed those previously reported for catalysts supported by either silica or polymer immobilized through one of the nitrogen atoms of TsDPEN. While the high ee's were also maintained during recycle studies, the conversion dropped steadily over the first three runs due to gradual leaching of the ruthenium. [ABSTRACT FROM AUTHOR]

The identification of drug candidates inhibiting specific cellular functions in cancer cell progression is reflected as a key in cancer treatment. The overexpression of epidermal growth factor receptor, EGFR is witnessed in a huge number of cancers. Hence targeting the EGFR and its downstream signaling cascades are considered as a coherent approach in cancer therapy. Keeping this in view, we have synthesized six 4,4‐Difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene/boron‐dipyrromethene (BODIPY) compounds, 1–6. Absorption, distribution, metabolism and excretion (ADME) and Lipinski's drug likeness of compounds 1–6 was predicted revealing that they exhibited promising physicochemical properties for oral bioavailability. Molecular docking results revealed that compound 6 displayed highest lipophilicity, hence strongest binding to the protein (ΔG=−8.78 kcal/mol) as compared to compounds 4 and 5. The density functional calculations have been investigated to validate the evidence about the reactivity of the compounds as inhibitors. These results were illustrated in terms of the chemical reactivity descriptors and the molecular electrostatic potential (MEP). Compound 6 showed the highest lying HOMO (highest occupied molecular orbital), the smallest energy gap between the FMOs (Frontier molecular orbitals) and the lowest basicity index, all of these parameters could affect the binding affinity, to different extents, to impact the degree of the binding of compound 6 with the active protein sites. [ABSTRACT FROM AUTHOR]

Abstract: Palladium nanoparticles stabilized by heteroatom donor‐modified polystyrene‐based polymer immobilized ionic liquids (PdNP@HAD‐PIILP; HAD‐PPh2, OMe, NH2, CN, pyrrolidone) are highly efficient catalysts for the Suzuki‐Miyaura cross‐coupling in aqueous media under mild conditions. Catalyst modified with phosphine was consistently the most efficient as it gave high yields across a range of substrates under mild conditions at low catalyst loadings. Incorporation of polyethylene glycol into the phosphine modified immobilised ionic liquid support improved catalyst efficacy by improving dispersibility and facilitating access to the active site. Moreover, each of the heteroatom modified catalysts was more active than the corresponding unsubstituted imidazolium‐based polystyrene benchmark as well as commercial samples of Pd/C. Catalyst generated in situ from either [PdCl4]@PPh2‐PIILP or its PEGylated counterpart [PdCl4]@PPh2‐PEGPIILP, by reduction with phenylboronic acid, outperformed their pre‐formed counterparts for the vast majority of substrates examined. The turnover frequency of 16,300 h−1 obtained at room temperature is one of the highest to be reported for palladium nanoparticle‐catalysed Suzuki‐Miyaura cross‐coupling between 4‐bromoacetophenone and phenylboronic acid in aqueous media under such mild conditions. [ABSTRACT FROM AUTHOR]

The recently introduced BOPHY (i.e., symmetrical bis(pyrrole-BF2)) chromophore is a highly attractive building block for constructing linear molecules with extended π-conjugation running along the molecular backbone. In order to assess the level of electronic communication between the terminal groups in this type of supermolecule, we have examined selective protonation and oxidation of the bis-(N,N-dimethylanilino-styryl) derivative. The amino N atoms are separated by 22.6 Åvia a conjugated pathway but there is no indication of through-bond electronic coupling. Instead, the disparate pKa values and also reduction potentials found for one-electron oxidation of each aniline group are well explained in terms of very long-range electrostatic interactions. It is necessary, however, to allow for the effects of ion-pairing. As an interesting aside, it is shown that protonation can be achieved in a cast PMMA film by using a suitable photo-acid generator. [ABSTRACT FROM AUTHOR]

A new type of 1,4-bis(diphenylphosphino)-1,3-butadiene-bridged diphosphine was synthesized using zirconium-mediation.

Issues concerning the unexpected formation of 3,6-dihydro-1H-pyridin-2-ones from the decarboxylative carbonylation of 5-vinyloxazolidin-2-ones using a palladium catalyst are discussed. These delta-lactams are produced in high yields from this regioselective process, and further research into the reaction pathway and prospective uses for these lactams is being undertaken.

A homologous series of triaryl-like KITPHOS-type monophosphines containing one, two, or three bulky 12-phenyl-9,10-dihydro-9,10-ethenoanthracene (KITPHOS) units have been developed, and the influence of increasing steric bulk on their efficacy as ligands in gold(I)-catalyzed carbon-heteroatom bond-forming cyclizations has been investigated. Detailed solution NMR studies on Ph-TRISKITPHOS, its oxide, and the corresponding gold(I) chloride adduct identified a conformational exchange process involving a concerted librational motion of the individual anthracene-derived organic substituents about their P-C bonds. The cessation of this motion at reduced temperatures lowers the molecular symmetry such that the two C6H4 rings in each of the KITPHOS units become inequivalent; a lower energy process involving restricted rotation of the biaryl-like phenyl ring has also been identified. Electrophilic gold(I) complexes of these triaryl-like KITPHOS monophosphines catalyze the 5-exo-dig cycloisomerization of propargyl amides to afford the corresponding methylene oxazolines, which were used in a subsequent tandem carbonyl-ene reaction to afford functionalized 2-substituted oxazolines. A comparative survey revealed that catalyst efficiency for cycloisomerization decreases in the order MONOKITPHOS = BISKITPHOS > PPh3 > TRISKITPHOS. The optimum system also catalyzes the selective 6-endo-dig cyclization of 2-alkynylbenzyl alcohols, 2-alkynylbenzoic acid, and 2-phenylethynyl benzamides; gratifyingly, in several cases the yields obtained are markedly higher and/or reaction times significantly shorter than those previously reported for related gold catalysts. Moreover, these are the first examples of gold(I)-catalyzed 6-endo-dig cycloisomerizations involving 2-phenylethynyl benzamides and, reassuringly, the optimum gold(I)/MONOKITPHOS systems either rivaled or outperformed existing silver or palladium-based catalysts. The steric parameters of this homologous series of phosphines have been quantified and compared with selected triarylphosphines using a combination of Solid-G calculations, to determine the percentage of the metal coordination sphere shielded by the phosphine (the G parameter), and Salerno molecular buried volume calculations (SambVca) to determine the percent buried volume (%Vbur); the corresponding Tolman cone angles have also been determined from correlations. [ABSTRACT FROM AUTHOR]

Helically chiral N,N,O,O-boron chelated dipyrromethenes showed solution-phase circularly polarized luminescence (CPL) in the red region of the visible spectrum (λem(max) from 621 to 663 nm). The parent dipyrromethene is desymmetrised through O chelation of boron by the 3,5-ortho-phenolic substituents, inducing a helical chirality in the fluorophore. The combination of high luminescence dissymmetry factors (∣glum∣ up to 4.7 × 10–3) and fluorescence quantum yields (ΦF up to 0.73) gave exceptionally efficient circularly polarized red emission from these simple small organic fluorophores, enabling future application in CPL-based bioimaging. [ABSTRACT FROM AUTHOR]

Thispaper reports the first examples of Suzuki–Miyauracross-couplings involving aryl- and naphthylphosphonate-based boronateesters as the nucleophilic partner. A systematic comparison of theperformance of biaryl-like KITPHOS- and XPHOS-based systems revealedthat, between them, an electronically and sterically diverse rangeof substrates can be coupled with remarkable efficiency to affordhigh yields of the corresponding biaryl and heterobiaryl monophosphonates.The use of an aryl- and naphthylphosphonate-based boronate ester asthe coupling partner presents an alternative and potentially complementarypathway to existing couplings in which the aryl- or naphthylphosphonateunit is typically introduced as the electrophile. The potential advantagesassociated with the use of this new class of coupling partner wereclearly demonstrated by the palladium-catalyzed reaction between diethyl[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]phosphonateand 1-bromo-2-methoxynaphthalene that gave the correspondingbiaryl monophosphonate in 56% yield, a marked improvement on the 6%yield obtained from the reaction between 2-methoxy-1-naphthylboronicacid and diethyl (2-bromophenyl)phosphonate with the samecatalyst under the same conditions. The potential utility of thisnew coupling combination was demonstrated by reducing one of the products,2-methoxy-1-(2′-diethoxyphosphorylphenyl)naphthylene,to the corresponding primary phosphine, which was subsequently convertedinto a diastereoisomeric mixture of the R,R-hexane-2,5-diol-derived phospholane in reasonable yield. [ABSTRACT FROM AUTHOR]

The asymmetric Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene and the Mukaiyama-aldol reaction between methylpyruvate and 1-phenyl-1-trimethylsilyloxyethene have been catalysed by heterogeneous copper(II)-bis(oxazoline)-based polymer immobilised ionic liquid phase (PIILP) systems generated from a range of linear and cross linked ionic polymers. In both reactions selectivity and ee were strongly influenced by the choice of polymer. A comparison of the performance of a range of Cu(II)-bis(oxazoline)-PIILP catalyst systems against analogous supported ionic liquid phase (SILP) heterogeneous catalysts as well as their homogeneous counterparts has been undertaken and their relative merits evaluated. [ABSTRACT FROM AUTHOR]

A linear cation-decorated polymeric support with tuneable surface properties and microstructure has been prepared by ring-opening metathesis polymerisation (ROMP) of a pyrrolidinium-functionalised norbornene-based monomer with cyclooctene. The derived peroxophosphotungstate-based polymer-immobilised ionic liquid phase (PIILP) catalyst is an efficient and recyclable system for the epoxidation of allylic alcohols and alkenes, with only a minor reduction in performance on successive cycles. [ABSTRACT FROM AUTHOR]

Abstract: Lewis acid platinum and palladium complexes of (S)-Me2-CATPHOS catalyse the carbonyl-ene reaction between allylbenzene derivatives and ethyl trifluoropyruvate to give the expected α-hydroxy esters with ee’s up to 97%, while the corresponding reaction involving 2-allylfuran and thiophene was exclusively selective for Friedel–Crafts-type reactivity and gave the corresponding 2-hydroxy-trifluoromethyl ethyl esters in good yield and moderate to good enantioselectivity. [Copyright &y& Elsevier]

Abstract: 2-Aryl-5,5-bisoxazolin-2-yl[1,3]dioxanes 5, which can be easily prepared in three steps from diethyl bishydroxymethylmalonate, amino alcohol and an aromatic aldehyde, have been used for the copper catalysed asymmetric cyclopropanation of styrene with ethyl diazoacetate in up to 99% ee for the trans-cyclopropane. Grafting onto a bromo-Wang resin produced an immobilised ligand 9 which gave the trans-cyclopropane in 65% ee. [Copyright &y& Elsevier]