Correction: Acridinedione as selective flouride ion chemosensor: a detailed spectroscopic and quantum mechanical investigation.

[This corrects the article DOI: 10.1039/C7RA11974G.].

Palladium-Catalyzed Carbonylative Synthesis of α-Branched Enones from Aryl Iodides and Arylallenes.

In this communication, an interesting carbonylation protocol for the preparation of α-branched enones has been established. Starting from readily available aryl iodides and allenes, with formic acid as the CO source and reductant, moderate to good yields of the desired enones were isolated. Although it is a carbonylation methodology, the use of a CO source can avoid the manipulation of CO gas directly.

Palladium-catalyzed intermolecular transthioetherification of aryl halides with thioethers and thioesters.

Functional group transfer reactions are an important synthetic tool in modern organic synthesis. Herein, we developed a new palladium-catalyzed intermolecular transthioetherification reaction of aryl halides with thioethers and thioesters. The synthetic utility and practicality of this catalytic protocol are demonstrated in a wide range of successful transformations (>70 examples).

Palladium-Catalyzed Synthesis of 1,2-Diketones from Aryl Halides and Organoaluminum Reagents Using -Butyl Isocyanide as the CO Source.

In this work, an interesting and practical procedure for the synthesis of 1,2-diketones from aryl halides and organoaluminum reagents has been developed. Employing -butyl isocyanide as the CO source and palladium as the catalyst, the desired 1,2-diketones were isolated in good to excellent yields with good functional group tolerance. Concerning the reaction partners, besides aryl halides, both alkyl- and arylaluminum reagents were all suitable substrates here.

Direct C-H Bond Borylation of (Hetero)Arenes: Evolution from Noble Metal to Metal Free.

Organoboron compounds are among the most versatile and useful building blocks in modern synthetic chemistry. The past decades have seen impressive developments in the direct C-H bond borylation of (hetero)arenes in which the applied catalysts are shifting from noble metals to metal-free systems. This Highlight gives a brief summary on this evolution and focuses on recent elegant work in this field.

Benzene-1,3,5-triyl Triformate (TFBen)-Promoted Palladium-Catalyzed Carbonylative Synthesis of 2-Oxo-2,5-dihydropyrroles from Propargyl Amines.

In this letter, we developed a palladium-catalyzed procedure for the cyclocarbonylation of propargyl amines. Benzene-1,3,5-triyl triformate (TFBen) has been explored as the CO source and also as the key promotor. Various substituted 2-oxo-dihydropyrroles were produced in a facile manner in good yields (up to 90%).

Facile synthesis of supported Ru-Triphos catalysts for continuous flow application in selective nitrile reduction.

The selective catalytic hydrogenation of nitriles represents an important but challenging transformation for many homogeneous and heterogeneous catalysts. Herein, we report the efficient and modular solid-phase synthesis of immobilized Triphos-type ligands in very high yields, involving only minimal work-up procedures. The corresponding supported ruthenium-Triphos catalysts are tested in the hydrogenation of various nitriles.

Direct synthesis of adipic acid esters via palladium-catalyzed carbonylation of 1,3-dienes.

The direct carbonylation of 1,3-butadiene offers the potential for a more cost-efficient and environmentally benign route to industrially important adipic acid derivatives. However, owing to the complex reaction network of regioisomeric carbonylation and isomerization pathways, a selective practical catalyst for this process has thus far proven elusive. Here, we report the design of a pyridyl-substituted bidentate phosphine ligand (HeMaRaphos) that, upon coordination to palladium, catalyzes adipate diester formation from 1,3-butadiene, carbon monoxide, and butanol with 97% selectivity and 100% atom-economy under industrially viable and scalable conditions (turnover number > 60,000).

A selective route to aryl-triphosphiranes and their titanocene-induced fragmentation.

Triphosphiranes are three-membered phosphorus cycles and their fundamental reactivity has been studied in recent decades. We recently developed a high-yielding, selective synthesis for various aryl-substituted triphosphiranes. Variation of the reaction conditions in combination with theoretical studies helped to rationalize the formation of these homoleptic phosphorus ring systems and highly reactive intermediates could be isolated.

A Comparative Study on the Thermodynamics of Halogen Bonding of Group 10 Pincer Fluoride Complexes.

The thermodynamics of halogen bonding of a series of isostructural Group 10 metal pincer fluoride complexes of the type [(3,5-R - POCOP )MF] (3,5-R - POCOP =κ -C HR -2,6-(OPtBu ) with R=H, tBu, COOMe; M=Ni, Pd, Pt) and iodopentafluorobenzene was investigated. Based on NMR experiments at different temperatures, all complexes 1-tBu (R=tBu, M=Ni), 2-H (R=H, M=Pd), 2-tBu (R=tBu, M=Pd), 2-COOMe (R=COOMe, M=Pd) and 3-tBu (R=tBu, M=Pt) form strong halogen bonds with Pd complexes showing significantly stronger binding to iodopentafluorobenzene. Structural and computational analysis of a model adduct of complex 2-tBu with 1,4-diiodotetrafluorobenzene as well as of structures of iodopentafluorobenzene in toluene solution shows that formation of a type I contact occurs.

Homogeneous cobalt-catalyzed reductive amination for synthesis of functionalized primary amines.

The development of earth abundant 3d metal-based catalysts continues to be an important goal of chemical research. In particular, the design of base metal complexes for reductive amination to produce primary amines remains as challenging. Here, we report the combination of cobalt and linear-triphos (bis(2-diphenylphosphinoethyl)phenylphosphine) as the molecularly-defined non-noble metal catalyst for the synthesis of linear and branched benzylic, heterocyclic and aliphatic primary amines from carbonyl compounds, gaseous ammonia and hydrogen in good to excellent yields.

Transfer-dehydrogenation of secondary alcohols catalyzed by manganese NNN-pincer complexes.

Novel catalytic systems based on pentacarbonylmanganese bromide and stable NNN-pincer ligands are presented for the transfer-dehydrogenation of secondary alcohols to give the corresponding ketones in good to excellent isolated yields. Best results are obtained using di-picolylamine derivatives as ligands and acetone as an inexpensive hydrogen acceptor. Besides high activity for benzylic substrates, aliphatic alcohols, as well as steroid derivatives, are readily oxidized in the presence of the optimal phosphorus-free catalyst.

Nickel(ii) PECEP pincer complexes (E = O, S) for electrocatalytic proton reduction.

Nickel(ii) chloride and thiolate complexes with PECEP (E = O, S) pincer ligands were investigated as electrocatalysts for the hydrogen evolution reaction in CHCN in the presence of acetic acid and trifluoroacetic acid. The bis(thiophosphinite) (S,S) chloride complex reduced protons at the lowest overpotential in comparison with the bis(phosphinite) (O,O) and mixed phosphinite-thiophosphinite (O,S) complexes. A combination of electrochemical, NMR and UV-vis spectroscopic and mass spectrometric experiments provides mechanistic insights into the catalytic cycle for proton reduction to dihydrogen.

A general benzylic C-H activation and C-C coupling reaction of zirconocenes mediated by C-N bond cleavage in tert-butylisocyanide - unusual formation of iminoacyl complexes.

Reactions of the zirconocene alkyne complex [rac-(ebthi)Zr(η2-Me3SiC2SiMe3)] (rac-(ebthi) = rac-1,2-ethylene-1,1'-bis(η5-tetrahydroindenyl)) with tert-butylisocyanide and methylbenzenes were investigated. Depending on the stoichiometry, the solvent and the reaction temperature different products were obtained. Starting with the end-on coordination of the isocyanide to the zirconium centre (2), elevated reaction temperatures and an excess of tert-butylisocyanide resulted after the elimination of the alkyne in the formation of zirconocene η2-iminoacyl cyanide complexes 3a-d.

Two precatalysts for application in propargylic CH activation.

The complexes {bis[(2-diphenylphosphanyl)phenyl] ether-κP,P'}(η-norbornadiene)rhodium(I) tetrafluoridoborate, [Rh(CH)(CHOP)]BF, and {bis[(2-diphenylphosphanyl)phenyl] ether-κP,P'}[η-(Z,Z)-cycloocta-1,5-diene]rhodium(I) tetrafluoridoborate dichloromethane monosolvate, [Rh(CH)(CHOP)]BF·CHCl, are applied as precatalysts in redox-neutral atomic-economic propargylic CH activation [Lumbroso et al. (2013). Angew.

Site-Selective Carbonylative Synthesis of Structurally Diverse Lactams from Heterocyclic Amines with TFBen as the CO Source.

A palladium-catalyzed site-selective C-H carbonylation of heterocyclic amines for the synthesis of lactam motifs has been developed. The reaction of 3-thiophene methylamines, 2-thiophene methylamines, and tryptamines with benzene-1,3,5-triyl triformate (TFBen) as the CO source provides a series of structurally diverse lactams in moderate to high yields with excellent regioselectivities.

Molecularly Defined Manganese Catalyst for Low-Temperature Hydrogenation of Carbon Monoxide to Methanol.

Methanol synthesis from syngas (CO/H mixtures) is one of the largest manmade chemical processes with annual production reaching 100 million tons. The current industrial method proceeds at high temperatures (200-300 °C) and pressures (50-100 atm) using a copper-zinc-based heterogeneous catalyst. In contrast, here, we report a molecularly defined manganese catalyst that allows for low-temperature/low-pressure (120-150 °C, 50 bar) carbon monoxide hydrogenation to methanol.

Palladium-Catalyzed Oxidative Carbonylative Coupling of Arylallenes, Arylboronic Acids, and Nitroarenes.

In this Letter, a palladium-catalyzed multicomponent procedure for the selective synthesis of α-substituted α,β-unsaturated ketones has been developed. With readily available allenes, arylboronic acids, and nitroarenes as the substrates, the reaction proceeds selectively to the desired α-substituted enones. Notably, no manipulation of carbon monoxide gas is needed here, and Mo(CO) has been applied as a stable solid CO source instead.

Cobalt-Catalyzed Carbonylative Synthesis of Phthalimides from -(Pyridin-2-ylmethyl)benzamides with TFBen as the CO Source.

A cobalt-catalyzed direct carbonylative synthesis of phthalimide motifs from -(pyridin-2-ylmethyl)benzamides has been developed. Various phthalimide derivatives were obtained in moderate to excellent yields (up to 98%) by using 2-picolylamine as an efficient directing group and benzene-1,3,5-triyl triformate (TFBen) as a convenient CO surrogate.

Palladium-Catalyzed Carbonylative Coupling of Aryl Iodides with Alkenylaluminum Reagents.

A highly reactive catalytic system for the carbonylative coupling of aryl iodides with alkenylaluminum reagents has been developed. Various β-substituted γ,δ-unsaturated ketones were produced under mild conditions in good to excellent yields even under ppm level of palladium catalyst. Notably, this also represents the first example on carbonylative transformation of alkenylaluminum compounds.

Multi-dimensional zinc oxide (ZnO) nanoarchitectures as efficient photocatalysts: What is the fundamental factor that determines photoactivity in ZnO?

While bulk zinc oxide (ZnO) is of non-toxic in nature, ZnO nanoarchitectures could potentially induce the macroscopic characteristics of oxidative, lethality and toxicity in the water environment. Here we report a systematic study through state-of-the-art controllable synthesis of multi-dimensional ZnO nanoarchitectures (i.e.

Cobalt(II)-Catalyzed Alkoxycarbonylation of Aliphatic Amines via C-N Bond Activation.

The first cobalt-catalyzed deaminative alkoxycarbonylation reaction was described for the conversion of readily available primary alkyl amines to synthetically versatile esters with moderate to high yields. This transformation shows good functional group compatibility and can serve as a powerful tool for the modification of alkyl amine-containing complex natural products and drug molecules.

Inter-molecular hydrogen bonding in isostructural pincer complexes [OH-( POCOP )Cl] ( = Pd and Pt).

In the crystal structure of the isostructural title compounds, namely {2,6-bis-[(di--butyl-phosphan-yl)-oxy]-4-hy-droxy-phen-yl}chlorido-palladium(II), [Pd(CHOP)Cl], , and {2,6-bis-[(di--butyl-phosphan-yl)-oxy]-4-hy-droxy-phen-yl}chlorido-platinum(II), [Pt(CHOP)Cl], , the metal centres are coordinated in a distorted square-planar fashion by the POCOP pincer fragment and the chloride ligand. Both complexes form strong hydrogen-bonded chain structures through an inter-action of the OH group in the 4-position of the aromatic POCOP backbone with the halide ligand.

Carbonylative Transformation of Allylarenes with CO Surrogates: Tunable Synthesis of 4-Arylbutanoic Acids, 2-Arylbutanoic Acids, and 4-Arylbutanals.

In this Communication, procedures for the selective synthesis of 4-arylbutanoic acids, 2-arylbutanoic acids, and 4-arylbutanals from the same allylbenzenes have been developed. With formic acid or TFBen as the CO surrogate, reactions proceed selectively and effectively under carbon monoxide gas-free conditions.

[E(μ-NBbp)] (E = P, As) - group 15 biradicals synthesized from acyclic precursors.

The synthesis of Bbp stabilized biradicals of the type [E(μ-NBbp)] (E = P, As) (Bbp = 2,6-bis[bis(trimethylsilyl)methyl]phenyl) was investigated. Contrary to the established synthetic protocol for terphenyl substituted biradicals [E(μ-NTer)] by reduction of [ClE(μ-NTer)], the analogous Bbp substituted precursor [ClE(μ-NBbp)] could only be obtained in low yields. For this reason, a new synthesis had to be found to generate [E(μ-NBbp)].