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An improved synthesis for tryptophan-dehydrobutyrine diketopiperazine (TDD), a co-metabolite of the hybrid polyketide/non-ribosomal peptide hangtaimycin, starting from ʟ-tryptophan is presented. Comparison to TDD isolated from the hangtaimycin producer Streptomyces spectabilis confirmed its S configuration. The X-ray structure of the racemate shows an interesting dimerisation through hydrogen bridges. The results from bioactivity testings of hangtaimycin, TDD and the hangtaimycin degradation product HTM222 are given.

Anionic 1,4-dihydro-1,4-diphosphinines were synthesized from tricyclic 1,4-diphosphinines and isolated as blue powdery salts M[

Three azadiphosphiridine complexes were selectively synthesized, two of them revealing a W(CO)5 group P-to-P′ haptotropic shift and only one displayed a planar ring N atom. Theoretical studies on ring formation and geometry as well as on the P-to-P′ haptotropic shift are reported.

A nanocrystalline TiO2 dye-sensitized solar cell device consisting of dye 2 and fabricated with commercially available materials reaches a conversion efficiency of η = 1.20%. Dye 2 is a low-cost and easily prepared copper(i) molecular sensitizer.

The condensation of easily accessible and widely functionalizable 2,4,6-triaryl pyrylium salts with mixed anhydrides, formed in situ from α-functionalized sodium acetates and an anhydride solvent, leads in good yields to the corresponding 2,4,6-triaryl benzenes functionalized at their 1-position. 4-(Trifluoromethyl)benzoic anhydride has been proven as being the solvent of choice and ortho-disubstituted diphenyl ethers, triphenyl amines and phenyl carbazoles with different functionalizations are synthesized. In addition, sterically hindered anthracene diacetate is condensed with two bis-bromophenyl pyrylium salts which leads after intramolecular Yamamoto coupling to bicyclophanes. In these, the anthracene core is surrounded by phenylenes and protected from photooxidation, leading to a highly stable blue emitting material.

Hypoxia-inducible factor-1alpha (HIF-1alpha) constitutes the principal mediator of cellular adaptation to hypoxia in humans. Hydroxylation of proline residues on HIF-1alpha is recognized by the E3 ligase von Hippel-Lindau (VHL), leading to ubiquitin-dependent proteasomal degradation of HIF-1alpha. In this study, we performed a structure-guided and bioactivity-driven design of new VHL inhibitors with improved cellular activity at blocking HIF-1alpha degradation. With the prototypical ligand VH298 as starting point, our iterative and combinatorial optimization strategy focused on introducing chemical variability into the phenylene unit of the VHL ligand structure and encompassed further points of diversity. The exploitation of tailored phenylene fragments combined with the stereoselective installation of the (S)-configured methyl group at the benzylic position provided VHL ligands with superior binding affinity compared to VH298. Three high-resolution structures of VHL in complex with three new ligands were determined and bioactive conformations of these ligands were explored. The most potent inhibitor (compound 30) exhibited dissociation constants (Kd) lower than 40 nM, independently determined by fluorescence polarization (FP) and surface plasmon resonance (SPR). The improved binding affinity to VHL was accompanied by enhanced cellular potency of 30, considerably exceeding the stabilization of HIF-1alpha by established VHL inhibitors. Our work is anticipated to inspire future efforts towards HIF-1alpha stabilizers and our optimized ligands to serve as an excellent starting point for proteolysis-targeting chimeras (PROTACs) hijacking VHL.

Excellent Z → E conversion was observed in a group of macrocyclic azobenzenes which were accessible via a versatile synthetic route.

Experimental and theoretical studies are reported of the first two-coordinated Si0-isocyanide compound (SIDipp)Si═C═N-ArMes (1: SIDipp (NHC) = C[N(Dipp)CH2]2, ArMes = 2,6-dimesitylphenyl), supported by an N-heterocyclic carbene (NHC). A Si atom economic two-step synthesis of 1 involves a 2e reduction of the isocyanide-stabilized silyliumylidene salt [SiBr(CNArMes)(SIDipp)][B(ArF)4] (2[B(ArF)4], ArF = B(C6H3-3,5-(CF3)2)4) with KC8. 2[B(ArF)4] was obtained from SiBr2(SIDipp) after bromide abstraction with an equimolar mixture of Na[B(ArF)4] and ArMesNC. Exact adherence to the stoichiometry is crucial in the latter reaction, since 2[B(ArF)4] reacts with SiBr2(SIDipp) via isocyanide exchange to afford the disilicon(II) salt [Si2Br3(SIDipp)2)][B(ArF)4] (3[B(ArF)4]), the reaction leading to an equilibrium that favors 3[B(ArF)4] (Keq(298 K) = 10.6, ΔH° = -10.6 kJ mol-1; ΔS° = -16.0 J mol-1 K-1). 3[B(ArF)4] was obtained selectively from the 2:1 reaction of SiBr2(SIDipp) with Na[B(ArF)4] and fully characterized. Detailed studies of 1 reveal an intriguing structure featuring a planar CNHC-Si-C-N skeleton with a V-shaped geometry at the dicoordinated Si0 center, a slightly bent Si═C═N core, a CNHC-Si-CCNR 3c-2e out of plane π-bond (HOMO), and an anticlinal conformation of the SIDipp and ArMes substituents leading to axial chirality and the presence of two enantiomers, (Ra)-1 and (Sa)-1. Compound 1 displays structural dynamics in solution, rapidly interconverting the enantiomers. The silacumulene 1 is a potent Si(SIDipp) transfer agent as demonstrated by the synthesis and full characterization of the NHC-supported germasilyne (Z)-(SIDipp)(Cl)Si═GeArMes (4) from 1 and Ge(ArMes)Cl.

A μ2-(η1,η2)-dinuclear diphosphene complex having two W(CO)5 groups with dimethyl acetylenedicarboxylate, 4-phenyl-1,2,4-triazoline-3,5-dione and diethyl azodicarboxylate was applied to P-heterocyclic synthesis, i.e., using a singlet carbene-type reactivity of a homonuclear π-system assisted by a haptotropic shift thus rendering a more nucleophilic β phosphorus and, hence, a subsequent ring expansion.

Mixed-valence compounds feature the same atoms but in different formal oxidation states. This research field is largely dominated by metal-based solid-state chemistry and has been intensively studied in recent years. By contrast, the situation is different for molecular main group element compounds and to establish 1,1'-bifunctional groups remained a particular challenge. Here a detailed study on 1,1'-bifunctional mixed-valence main group compounds possessing a P-P bond is presented, and the fundamental role of the metal complex fragments is discussed. Based on the generation of a transient phosphanylidene-phosphinidenoid complex a dinuclear diphosphene complex was obtained possessing an unprecedented ambident reactivity, i.e., 1,2-addition or 1,1-addition products were obtained depending on the nature of the reagent. The 1,1-addition products represent stable hitherto unknown 1,1'-bifunctional phosphanylidene-phosphorane complexes which have been confirmed by X-ray diffraction studies. Detailed state-of-the-art DFT calculations provide insight into bonding and reaction pathways.

Although 1,2σ

Solution-processed and thermally annealed thin films from a series of nalkyl terminated anilino squaraines are systematically investigated regarding their structural and optical properties by means of X-ray diffraction (XRD) and spectroscopic ellipsometry (SE). Their characteristic intense double-hump-shaped absorbance spectra consisting of coupled H-aggregate and intermolecular charge transfer (ICT) resonance bands make them appealing for fundamental light−matter interaction studies, and their environmental sustainability invites for consumer optoelectronic applications. Now, the single-crystal structure of the n-pentyl anilino squaraine (nPSQ) provides a missing link to identify potential odd−even effects with respect to the terminal alkyl chain for bulk crystals. While all single crystals adopt a triclinic unit cell with biaxial dielectric properties, the thin films condense into effectively uniaxial anisotropic thin films. Here, the inherently low sensitivity to the ut-ofplane complex refractive index of SE in reflection is reasonably compensated by adding transmission SE and transmission intensity data. With that, a general picture of the structural and dielectric properties of n-alkyl anilino squaraine thin films is launched, revealing that the terminal alkyl chain length affects the structural and optical properties in a twofold way: we observe a steady change which is superimposed by an anisotropic odd−even effect.

Five ligands with either nitrile or isonitrile metal binding motifs have been synthesized based on the 2,8- or 3,9-disubstituted Troger's base scaffold, respectively. These ligands self-assemble into dinuclear cyclic metallosupramolecular aggregates upon coordination to [(dppp)Pd(OTf)2 ] in a highly diastereoselective manner, by heterochiral self-sorting in a chiral self-discriminating manner as shown by ESI mass spectrometry, NMR spectroscopy, and single crystal XRD analysis. This observation is in contrast to earlier studies with ligands derived from Troger's base that have larger metal binding motifs and bis(nitrile) and bis(isonitrile) ligands based on other rigid dissymmetric cores such as [2.2]paracyclophanes. Thus, the combination of these slim metal binding motifs with the rigid v-shaped 2,8- or 3,9-disubstituted Troger's base scaffolds seems to be especially well preorganized to ensure high-fidelity social self-sorting behavior.

The proteolysis-targeting chimeras (PROTACs) have become an integral part of different stages of drug discovery. This growing field, therefore, benefits from advancements in all segments of the design of these compounds. Herein, an efficient and optimized synthetic protocol to various von Hippel-Lindau (VHL) ligands is presented, which enables easy access to multigram quantities of these essential PROTAC building blocks. Moreover, the elaborated synthesis represents a straightforward approach to further explore the chemical space of VHL ligands.

A new, mild and efficient protocol for the synthesis of trifluoromethyl(indolyl)phenylmethanols by the reaction of indoles with a variety of aromatic fluoromethyl ketones in the presence of K2CO3 (15 mol %) and n-Bu4PBr (15 mol %) in water. The desired products were obtained in good to excellent yields without requiring a column chromatographic purification. The reusability of the catalytic system and large-scale synthesis of indolyl(phenyl)methanols, which would further transform into biological active indole-derived compounds, are further advantages of this protocol.

Diels-Alder-reactions of a thiazol-2-thione-based, tricyclic 1,4-di-phosphinine were investigated, showing that the central aromatic π-system can react with various dienophiles. The reaction with 4-phenyl-1,2,4-triazoline-3,5-dione was special as the product revealed a remarkable sensitivity towards light, thus enabling the photochemical deprotection of the tricyclic 1,4-diphosphinine.

A protocol for the synthesis of mono- and bis-phosphanylated 1,3-dithiole-2-thiones 2 and 3 is presented. The reaction of 2 or 3 with hydrogen peroxide–urea or elemental sulfur led to the corresponding P(V) chalcogenide 1,3-dithiole-2-thiones 4–7. All compounds were characterized by 31P, 1H and 13C NMR and IR spectroscopy and elemental analyses. Additionally, compounds 3 and 4 were analysed by single-crystal X-ray diffraction analysis. The reaction of 3 with P(OEt)3 led selectively to the tetrakis-phosphanylated tetrathiafulvalene derivative IIvia a reductive C2,C2 coupling reaction. A thorough computational analysis for the mechanism of phosphite-mediated reductive dimerization of 1,3-dithiole-2-thiones was performed.

Various BRAF kinase inhibitors were developed to treat cancers carrying the BRAFV600E mutation. First-generation BRAF inhibitors could lead to paradoxical activation of the MAPK pathway, limiting their clinical usefulness. Here, we show the development of two series of BRAF-targeting PROTACs and demonstrate that the exchange of the inhibitor scaffold from vemurafenib to paradox-breaker ligands resulted in BRAF degraders that did not cause paradoxical ERK activation. Članek objavljen 5. maja 2022. Nasl. z nasl. zaslona. Opis vira z dne 6. 5. 2022. Članek vsebuje supplement informacijo, [49 str.] Bibliografija: str. 735-736. Abstract. Cancer Research UK programme ARRS, program, P1-0208 ARRS

P-OTEMP 1,3,2-heterophospholane tungsten complexes with different thermal stabilities were used to generate transient phosphanoxyl complexes which allow for a first-time radical polymerisation of acrylonitrile based on this methodology.

Naturally occurring compounds represent a vast pool of pharmacologically active entities. One of such compounds is andrographolide, which is endowed with many beneficial properties, including the activity against severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). To initiate a drug repurposing or hit optimization campaign, it is imperative to unravel the primary mechanism(s) of the antiviral action of andrographolide. Here, we showed by means of a reporter gene assay that andrographolide exerts its anti-SARS-CoV-2 effects by inhibiting the interaction between Kelch-like ECH-associated protein 1 (KEAP1) and nuclear factor erythroid 2-related factor 2 (NRF2) causing NRF2 upregulation. Moreover, we demonstrated that subtle structural modifications of andrographolide could lead to derivatives with stronger on-target activities and improved physicochemical properties. Our results indicate that further optimization of this structural class is warranted to develop novel COVID-19 therapies.

Prototypical n-alkyl terminated anilino squaraines for photovoltaic applications show characteristic double-hump absorption features peaking in the green and deep-red spectral range. These signatures result from coupling of an intramolecular Frenkel exciton and an intermolecular charge transfer exciton. Crystalline, textured thin films suitable for polarized spectro-microscopy have been obtained for compounds with n-hexyl (nHSQ) and n-octyl (nOSQ) terminal alkyl chains. The here released triclinic crystal structure of nOSQ is similar to the known nHSQ crystal structure. Consequently, crystallites from both compounds show equal pronounced linear dichroism with two distinct polarization directions. The difference in polarization angle between the two absorbance maxima cannot be derived by spatial considerations from the crystal structure alone but requires theoretical modeling. Using an essential state model, the observed polarization behavior was discovered to depend on the relative contributions of the intramolecular Frenkel exciton and the intermolecular charge transfer exciton to the total transition dipole moment. For both nHSQ and nOSQ, the contribution of the charge transfer exciton to the total transition dipole moment was found to be small compared to the intramolecular Frenkel exciton. Therefore, the net transition dipole moment is largely determined by the intramolecular component resulting in a relatively small mutual difference between the polarization angles. Ultimately, the molecular alignment within the micro-textured crystallites can be deduced and, with that, the excited state transitions can be spotted., Comment: 12 pages, 8 figures

Metal complexes displaying antiplatelet properties is a promising research area. In our methodology, Platelet-Activating Factor (PAF), the most potent lipid pro-inflammatory mediator, serves as a biological probe. The antiplatelet activity is exerted by the inhibition of the PAF-induced aggregation in washed rabbit platelets (WRPs) and in rabbit plasma rich in platelets (rPRPs). Herein, the synthesis and biological investigation of a series of organometallic tin(II) and tin(IV) complexes, featuring the oxygen tripodal Kläui ligands [(η5-C5R5)Co{P(OEt)2O}3]−, {R = H, (LOEt−); Me (L*OEt−)}, are reported. Reaction of NaLOEt (1a) and NaL*OEt (1b) with SnCl2, yielded the rare four-coordinate LOEtSnCl (2a) and L*OEtSnCl (2b) complexes. Accordingly, LOEtSnPh3 (3a) and L*OEtSnPh3 (3b) were prepared, starting from Ph3SnCl. Characterization includes spectroscopy and X-ray diffraction studies for 2a, 2b and 3b. The antiplatelet activity of the lead complexes 2b and 3a (IC50 = 0.5 μΜ) is superior compared to that of 1a and 1b, while both complexes display a pronounced inhibitory activity against thrombin (IC50 = 1.8 μM and 0.6 μM). The in vitro cytotoxic activities of 3a and 2b on human Jurkat T lymphoblastic tumor cell line is higher than that of cisplatin.

Experimental and theoretical studies are reported of the first two-coordinated Si

Synthesis of the tricyclic 1,3-dithiole-2-thione-derived 1,4-dihydro-1,4-diphosphinine is presented using a base-induced ring formation protocol and chloro(diethylamino)(1,3-dithiole-2-thion-4-yl)phosphane as the starting point. P-oxidation reactions of dihydrodiphosphinine by chalcogens led to bis(P-oxide), bis(P-sulfide), or bis(P-selenide), respectively; all tricyclic compounds were obtained as cis/trans mixtures. 1,4-Dihydro-1,4-diphosphinine was converted into 1,4-dichloro-1,4-dihydro-1,4-diphosphinine. This compound is almost insoluble in organic solvents, furnished selectively the trans-bis(amino) derivative upon a 2-fold P-substitution reaction with the weak nucleophile potassium bis(trimethylsilyl)amide, and reacted also with alcohols ROH (R = nBu, iPr, tBu) to give cis/trans mixtures of the corresponding bis(alkoxy) derivatives. Furthermore, the dichloro derivative could be reduced to a 1,4-diphosphinine using PnBu3, but, unfortunately, the stubbornly insoluble product could be neither purified nor crystallized. Despite this, we achieved a thermal [4 + 2] cycloaddition reaction of this first CPS-ternary compound with diethylacetylene dicarboxylate to obtain the corresponding diphosphabarrelene, thus providing indirect evidence for the aromatic tricyclic diphosphinine. Detailed density functional theory studies on the formation of 1,4-diphosphinine provided insights into formation pathways as well as NMR, IR, and UV/vis data.

The synthesis, isolation and structural characterization of the novel heteroleptic copper(I) complexes [Cu(RDABdipp)(LCOOMe)](PF6) (R = H (3), R = Me (4)) incorporating the sterically demanding 1,4-diaza-1,3-butadienes RDABdipp (R = H, Me; dipp = 2,6-diisopropylphenyl) is reported. 3 and 4 were isolated in high yields and spectroscopically characterized. The synthetic strategy includes the in situ reaction of the bis-acetonitrile intermediates [Cu(RDABdipp)(NCMe)2](PF6), (R = H (1), R = Me (2)) with the required amounts of the methyl-2-(pyridin-2-yl)-quinoline-4-carboxylate (LCOOMe) that was used as the ancillary ligand. 3 and 4 are rare examples of heteroleptic copper(I) complexes comprising RDABdipp and an ancillary α-diimine ligand, while 3 is the first crystallographically characterized example of this class of compounds. As a side product during the formation of 3 and 4, the homoleptic complex [Cu(LCOOMe)2](PF6) (5) is detected, that has been independently synthesized, for comparison. All the products were characterized by elemental analysis, FT–IR, UV–Vis and NMR spectroscopy. The molecular structures of 2·CH2Cl2, 3 and 5·CHCl3 were elucidated by single-crystal X-ray diffraction.

A titanocene‐catalyzed regiodivergent radical arylation is described that allows access to either enantiomerically pure tetrahydroquinolines or indolines from a common starting material. The regioselectivity of epoxide opening that results in the high selectivity of heterocycle formation is controlled by two factors, the absolute configuration of the enantiopure ligands of the (C5H4R)2TiX2 catalyst and the inorganic ligand X (X=Cl, OTs). The overall reaction is atom‐economical and constitutes a radical Friedel–Crafts alkylation., Indolines and tetrahydroquinolines are formed from the same substrates by titanocene catalysis. The absolute configuration of the cyclopentadienyl ligand and the inorganic ligand determine the regioselectivity of the ring opening and diastereoselectivity of tje radical arylation in the regiodivergent radical arylation of epoxides.

The modification of amino acids leads to valuable building blocks for the synthesis of bioactive compounds. By keeping the amino group protected, the carboxylic acid functionality can be converted in two steps into an imidazole moiety via a Davidson-like heterocyclization. This reaction allows for a combinatorial approach, in which two positions at the heterocycle can be modified. Herein, we report the synthesis of such imidazole derivatives by employing N-protected cyclohexylalanine as the starting material. Different α-halo ketones were used and two points of diversity, positions 4 and 5, were examined. The structure of the final imidazole derivatives was confirmed by three X-ray crystal structure analyses and their protease inhibiting activities were evaluated.

While P(v) 1,2-oxaphosphetanes were investigated in great detail over the past decades, the knowledge about P(v) 1,2-thiaphosphetanes is rather scarce, and P(iii) derivatives are unknown. Herein, we present the synthesis of the first P(iii) complex derivatives formed in the coordination sphere of group 6 metals and, additionally, the first unligated P(iii) 1,2-thiaphosphetanes. The latter display an unusually low HOMO-LUMO gap thus constituting excellent candidates for redox-cycling organocatalysts.

Although 1,2σ5λ5-oxaphosphetanes have been known for a long time, the “low-coordinate” 1,2σ3λ3-oxaphosphetanes have only been known since their first synthesis in 2018 via decomplexation. Apart from ligation of this P-heterocycle to gold(I)chloride and the oxidation using ortho-chloranil, nothing on their chemistry has been reported so far. Herein, we describe the synthesis of new 1,2σ3λ3-oxaphosphetane complexes (3a–e) and free derivatives (4a–e), as well as reactions of 4a with chalcogens and/or chalcogen transfer reagents, which yielded the P-chalcogenides (14–16a; Ch = O, S, Se). We also report on the theoretical results of the reaction pathways of C-phenyl-substituted 1,2 σ3λ3-oxaphosphetanes and ring strain energies of 1,2σ4λ5-oxaphosphetane P-chalcogenides.

A combinatorial method was devised and applied for the design and identification of substrate-analogue inhibitors of therapeutically relevant serine proteases, such as thrombin and factor Xa. We conceptualized imino acid derived diketomorpholines as generally applicable key intermediates prepared through solid-phase synthesis and prone to be cleaved with primary amines in a traceless fashion. The approach led to a compound library whose members were prepared under bioassay-compatible conditions and directly subjected to the in situ evaluation, allowing a fast prediction of hit compounds. Highly active inhibitors for serine proteases of the coagulation cascade have been identified. The most potent dual inhibitor, 16K, has a binding affinity of 23.9 nM to thrombin and 32.8 nM to factor Xa.

N,N-Diphenylamino- and N,N-dicyclohexylamino-substituted dichlorophosphane W(CO)5 complexes 1a,b were used to generate thermally very labile Li/Cl phospinidenoid W(CO)5 complexes 2a,b. The formation of transient complex 2a was confirmed via low-temperature 31P{1H} NMR spectroscopy, but further strong evidence for the formation of transient complexes 2a,b was obtained from reactions with methanol and methylamine as formal E–H insertions (E = O, N) furnished complexes 3a,b and 4a. By using toluene in the absence of donor ligands, the primarily nucleophilic complexes 2a,b were converted into electrophilic terminal phosphinidene complexes 5a,b which was deduced from specific trapping reactions using tolane, 1-pentene and 1-hexene and thus obtained 1H-phosphirene 6 and phosphirane complexes 7 and8. The state-of-the-art DFT calculations reveal insights into the possible reaction pathways and exclude a direct reaction of 2a,b with alkene trapping reagents.

While a variety of compounds containing planar tetracoordinated carbon (ptC), the so-called anti-van't Hoff/Le Bel carbon, are known experimentally, stable systems containing planar tetracoordinated silicon (ptSi) are barely known. As part of our studies on the application of stereoelectronically well-defined transition-metal fragments to stabilize silicon in unprecedented bonding modes, we report herein the synthesis and full characterization of a series of thermally stable complexes of the general formula [Tp'(CO)2MSiC(R1)C(R2)M(CO)2Tp'] (M = Mo, W; R1 = R2 = Me or R1 = H, R2 = SiMe3, Ph; Tp' = κ3-N,N',N″-hydridotris(3,5-dimethylpyrazolyl)borate), which incorporate a ptSi atom in addition to two ptC atoms. The complexes were obtained by reacting the metallasilylidyne complexes [Tp'(CO)2M≡Si-M(CO)2(PMe3)Tp'] with alkynes R1C≡CR2 and were comprehensively analyzed by experimental studies and quantum chemical calculations. The analyses revealed that the ptSi atom is embedded in a tricyclic trapezoidal core featuring one internal SiC2 and two outer M-Si-C three-membered rings, which are fused via two Si-C bonds. The structural peculiarities evoked by the presence of an anti-van't Hoff/Le Bel ptSi center, such as the short M-Si bonds, a nearly linear M-Si-M spine, long M-C bonds, and the presence of two planar tetracoordinated carbon atoms were elucidated by a detailed analysis of the electronic structure, suggesting that one factor for the stabilization of the ptSi geometry is the aromaticity of the central SiC2 ring having two delocalized π electrons. Remarkably, the results further indicate the existence of both anti-van't Hoff/Le Bel carbon and silicon centers next to each other in the isolated complexes.

A phosphanido-type bridged bis(imidazolium) salt, readily prepared in two steps via reductive deselenization of a tricyclic 1,4-diphosphinine diselone, affords access to a novel anionic P-functional tricyclic bis(NHC) via deprotonation. The former also offers a P-functionalization/deprotonation sequence to access the first mixed P-substituted tricyclic bis(NHCs), as well as coordination of the phosphorus centers to rhodium(I) fragments.

A rational approach to phosphaquinomethane metal(0) complexes, based on dearomatization of the phenylene unit in [W(CO)5](R)P(Cl)-C6H5-CPh2, is described, including theoretical studies on mechanisms and structures. Furthermore, the first phosphaquinone tungsten complex with reversible redox properties is reported thus illustrating the beneficial stabilization of ligation.

Although the chemistry of frustrated Lewis pairs (FLPs) has seen tremendous developments, investigations on anionic, mono-molecular FLPs are still scarce and 1,3-zwitterions are unknown. Herein, synthesis of a K/OR phosphinidenoid complex bearing a Si–Cl function is reported and, hence, can serve as a synthetic equivalent for a 1,3-zwitterion to allow access to rare and novel heterocyclic P-ligands.

A new, mild and efficient protocol for the synthesis of trifluoromethyl(indolyl)phenylmethanols by the reaction of indoles with a variety of aromatic fluoromethyl ketones in the presence of K2CO3 (15 mol %) and n-Bu4PBr (15 mol %) in water. The desired products were obtained in good to excellent yields without requiring a column chromatographic purification. The reusability of the catalytic system and large-scale synthesis of indolyl(phenyl)methanols, which would further transform into biological active indole-derived compounds, are further advantages of this protocol.

A new, mild and efficient protocol for the synthesis of trifluoromethyl-indolyl-phenylethanols by the reaction of indoles with a variety of aromatic fluoromethyl ketones in the presence of K2CO3 (15 mol%) and nBu4PBr (15 mol%) in water. The desired products were obtained in good to excellent yields without requiring the column chromatography purification. The reusability of the catalytic system and large-scale synthesis of indolyl-phenylethanols, which would further transform into biological active indole-derived compounds, are further advantages of this protocol.

Synthesis of the first tricyclic bis(carbenes) with facially opposed imidazole-2-ylidenes and two linking phosphorus centres in different oxidation states is presented using a modular, high-yield synthetic route. The formation of homo bimetallic coinage metal(i) complexes provides a first glimpse on their potential use.