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C10a‐Acetoxylated perhydroazepino[1,2‐a]‐indoles, accessible via visible light‐mediated sensitized photooxygenation of cyclo‐hepta[b]indoles, are precursors to structurally elaborate carbon‐centered radicals. Their photoredox‐catalyzed SET reduction by phenothiazine or phenoxazine photocatalysts, followed by fragmentation and C−O bond cleavage, liberates tricyclic α‐amino‐α‐carbonyl radicals that readily engage in radical addition reactions with silyl enol ethers and silyl ketene acetals. The C−C functionalized azepinoindole[1,2‐a]indoles are useful building blocks for the synthesis of polycyclic indole derivatives as shown by the controlled borohydride reduction of a C10a‐methylenecarboxylate derivative, which leads stereoselectively to tetracyclic azepino[1,2‐a]furo[3,2‐b]indoles. The photocatalytic method developed herein is also suitable for the radical functionalization of simple α‐acetoxy acetophenones. [ABSTRACT FROM AUTHOR]

A series of N‐doped Benzo[b]fluoranthenes was synthesized. Specifically varying the position of the Nitrogen atom in all four positions of the bottom ring. In the last reaction step the five‐membered ring of the unsubstituted core structure is formed by palladium catalyzed CH‐activation. This synthetic approach allows for the selective introduction of heteroatoms into the core structure and leads to four regioisomeric products. Subsequently the optical and electrochemical properties of these polyaromatic heterocycles were compared. DFT/TD‐DFT and NICS calculations were performed to further analyze, how the position of Nitrogen impacts the overall characteristics of the molecules. This composes a thorough study on the chemical behavior of N‐doped Benzo[b]fluoranthenes. [ABSTRACT FROM AUTHOR]

A new synthetic route to 1H-1,2,3-triazole-4,5-dithiols (tazdtH2) as ligands for the coordination of NiII, PdII, PtII and CoIII via the dithiolate unit is presented. Different N-protective groups were introduced with the corresponding azide via a click-like copper-catalyzed azide-alkyne [3 + 2] cycloaddition (CuAAC) and fully characterized by NMR spectroscopy. Possible isomers were isolated and an alternative synthetic route was investigated and discussed. After removal of the benzyl protective groups on sulfur by in situ-generated sodium naphthalide, complexes at the [(dppe)M] (M = Ni, Pd, Pt), [(PPh3)2Pt] and [(η5-C5H5)Co] moieties were prepared and structurally characterized by XRD analysis. In this process, the by-products 11 and 12 as monothiolate derivatives were isolated and structurally characterized as well. With regioselective coordination via the dithiolate unit, the electronic influence of different metals or protective groups at N was investigated and compared spectroscopically by means of UV/Vis spectroscopy and cyclic voltammetry. Complex [(η5-C5H5)Co(5c)] (10), is subject to a dimerization equilibrium, which was investigated by temperature-dependent NMR and UV/Vis spectroscopy (solution and solid-state). The thermodynamic parameters of the monomer/dimer equilibrium were derived. [ABSTRACT FROM AUTHOR]

Spirocyclic diindenothiophenes were prepared by cyclization of tosylhydrazones, readily available from ketones, with 3,4-dibromo-2,5-bis(2-bromphenyl)thiophene. For bicyclic ketones, the bis-spirocycles were formed with very good diastereoselectivity. [ABSTRACT FROM AUTHOR]

The reaction of the singlet biradical [P(μ-NTer)]2 with various aldehydes selectively yielded the corresponding [2.1.1]-bicyclic addition products in a very fast reaction. All products were fully characterized, including by NMR and vibrational spectroscopy as well as single-crystal X-ray diffraction. The mechanism of the addition was investigated theoretically using high-level ab initio methods (CCSD(T) with triple- and quadruple-zeta basis sets) and corresponds to a concerted cycloaddition reaction with a very low activation barrier. For comparison, the mechanisms of the literature-known cycloadditions of H2, alkenes, and alkynes were also studied, indicating a similar reaction profile for all unsaturated reactants. [ABSTRACT FROM AUTHOR]

The oxidation of silylated hydrazine, (Me3Si)2N−N(H)SiMe3, with silver salts led to the formation of a highly labile hydrazinium‐yl radical cation, [(Me3Si)2N−N(H)SiMe3].+, at very low temperatures (decomposition > −40 °C). EPR, NMR, DFT and Raman studies revealed the formation of a nitrogen‐centered radical cation along the N−N unit of the hydrazine. In the presence of the weakly coordinating anion [Al{OCH(CF3)2}4]−, crystallization and structural characterization in the solid state were achieved. The hydrazinium‐yl radical cation has a significantly shortened N−N bond and a nearly planar N2Si3 framework, in contrast to the starting material. According to DFT calculations, the shortened N−N bond has a total bond order of 1.5 with a π‐bond order of 0.5. The π bond can be regarded as a three‐π‐electron, two‐center bond. [ABSTRACT FROM AUTHOR]

This article provides the first single-crystal XRD-based structure of enantiopure (R)-baclofen (form C), C10H12ClNO2, without any co-crystallized substances. In the enantiopure title compound, the molecules arrange themselves in an orthorhombic crystal structure (space group P212121). In the crystal, strong hydrogen bonds and C--H...Cl bonds interconnect the zwitterionic molecules. [ABSTRACT FROM AUTHOR]

Ullazines and their π-expanded derivatives have gained much attention as active components in various applications, such as in organic photovoltaic cells or as photosensitizers for CO2 photoreduction. Here, we report the divergent synthesis of functionalized diazaullazines by means of two different domino-reactions consisting of either a Povarov/cycloisomerization or alkyne–carbonyl metathesis/cycloisomerization protocol. The corresponding quinolino-diazaullazine and benzoyl-diazaullazine derivatives were obtained in moderate to good yields. Their optical and electronic properties were studied and compared to related, literature-known compounds to obtain insights into the impact of nitrogen doping and π-expansion. [ABSTRACT FROM AUTHOR]

Four different isomeric azadibenzo[a,e]pyrenes (benzo[4,10]anthra[9,1‐gh]isoquinolines and benzo[4,10]anthra[1,9‐fg]isoquinolines) were prepared by combination of Pd‐catalyzed Sonogashira and Suzuki cross‐coupling, Brønsted acid mediated cycloisomerization and Pd‐catalysed CH‐activation reactions. The optical properties have been studied by steady‐state absorption and emission spectroscopy in different solvents and during acid titration. Trifluoroacetic acid protonation strongly affects absorption and emission properties, with variations depending on the position of the nitrogen atom of the specific compound. Electrochemical analysis showed distinct oxidation and reduction potentials. DFT calculations provided further insights into electronic properties. [ABSTRACT FROM AUTHOR]

The Buchwald–Hartwig amination allows an efficient and convenient synthesis of biologically and pharmaceutically important acridones by formation of a six-membered ring. With the described method, a number of derivatives have been synthesized in up to 95% yield by using a variety of anilines as well as benzylic and aliphatic amines. [ABSTRACT FROM AUTHOR]

This report describes a one‐pot multi‐step procedure to obtain double azahelicenes via nucleophilic fluorine substitution of 2,2‐di(2‐bromophenyl)‐1,1‐difluoroalkenes and palladium‐catalysed ring closing reaction. The developed synthesis approach allows easy diversification of substituents at all four fragments of the obtained X‐shaped aza[4,6]helicene entity. Yields range from 20 % to 60 % among 12 product examples. X‐ray single crystal analysis reveals formation of (P,P) and (M,M) enantiomer mixture of products. Optical and electrochemical properties of selected products were studied by performing UV/Vis absorption, photoluminescence and cyclic voltammetry measurements. Experimental results are supported by (TD)‐DFT, NICS and NICS2BC calculations. [ABSTRACT FROM AUTHOR]

The terminal phosphine groups at the tungsten bisphosphine alkyne complex [Tp*W(CO)(I)(η²-C,C'-Ph2PC2PPh2)] (2) {Tp* = hydridotris(3,4,5-trimethylpyrazolyl)borate} were selectively oxidized by common methods to form the alkyne complexes 2EE (E = O, S) with either two phosphine oxide or two phosphine sulfide substituents. The respective mono-oxidized analogues 2E (E = O, S) were obtained by subjecting the already oxidized intermediates [Tp*W(CO)(I)(η²-C,C'-Ph2P(E)C2H)] 1E (E = O, S) to a late-stage phosphine introduction at the complex template. These modulations of the peripheral alkyne moiety have a clear impact on the redox potential of the metal-based oxidation altering the W(II/III) potential by +0.1 V on average per oxidized phosphine. In contrast to the comparable redox behavior of 2O and 2S, the coordination behavior of these complex ligands differs substantially. XRD studies show that complex 2 and the sulfide 2Sact either as a P,P'- or P,S-chelate ligand leading to the dinuclear complexes [(2)PdCl2], 3, and [(2S)PdCl2], 3S. In contrast, the corresponding PdCl2 complex of the monoxide 2O is connected by the free phosphine group and the W-bonded iodide as a μ²-bridging ligand leaving the phosphine oxide pending. A similar binding mode was found for the trinuclear gold complex [(2)2Au][PF6] (5-PF6). Furthermore, these findings explain the undesired outcome in the reaction of [Pd(NCMe)4][BF4]2 with two equivalents of 2, which resulted in the iodide abstraction product [(2)PdI2] (4). [ABSTRACT FROM AUTHOR]

The synthesis of N-trimethylstannylamines of the type RN(SnMe3)H (stannylated anilines) with the sterically encumbered substituents R such as Ter [terphenyl, 2,6-bis(2,4,6-trimethylphenyl)-phenyl], Ar* [2,6-bis(diphenylmethyl)-4-methylphenyl], and Mes* (supermesityl, 2,4,6-tri- tert-butylphenyl) is described. These stannylated anilines were treated with BiCl3 leading to the formation of RN(H)BiCl2 (for R = Ter), ( RNH)3Bi (for R = Mes*), and RN(BiCl2)2 (for R = Ar*). The synthesis and structure of the starting material RN(SnMe3)H and the new aminobismuthanes are reported. [ABSTRACT FROM AUTHOR]

Polyalkynylated naphthalenes were obtained from easily available 2,3-dibromobenzoquinone. The developed methodology consists of a substitution of both carbonyl groups of the quinone moiety by lithium acetylide followed by a Pd-catalyzed cross-coupling reaction. Optical properties of selected compounds were studied. [ABSTRACT FROM AUTHOR]

P2X receptors (P2XRs) are ligand-gated membrane ion channels. ATP binds to open these ion channels and results in membrane depolarization. Hyperactivities and overexpression of P2XRs are related to various pathophysiological conditions such as chronic pain, inflammatory diseases, rheumatoid arthritis, various neurological disorders, and cancer. Inhibition of P2XRs is a potential drug target that is an emerging therapeutic tool for disease management. In the present study, 17 new compounds were synthesized based on 1,3-benzodioxole-5-carboxylic acid and were investigated for P2XRs inhibition. Ca2+ influx assay was performed on P2XRs expressed h -1321N1 astrocytoma cell lines. The synthesized compounds exhibited high potency and selectivity towards h -P2X4R and h -P2X7R. In silico studies were carried out that began with the development of a homology model for h -P2X7R with subsequent molecular docking studies of the most potent P2XRs antagonists. 9o (N -((2-bromo-4-isopropylphenyl)carbamothioyl)benzo[d] [1,3]dioxole-5-carboxamide) was found to have significant inhibitory potential and selectivity for h -P2X4R with an IC 50 ± SEM of 0.039 ± 0.07 μM. Whereas, 9q (N -(quinolin-8-ylcarbamothioyl)benzo[d] [1,3]dioxole-5-carboxamide) was selective and most potent antagonist for h -P2X7R with an IC 50 ± SEM of 0.018 ± 0.06 μM. Both antagonists, 9o and 9q, exhibited a non-competitive negative allosteric mode of antagonism. [Display omitted] • Synthesis of 1,3-benzodioxole N -carbamothioyl carboxamide derivatives. • Cytotoxicity assay for synthesized compounds. • Stable transfection of human P2XRs. • Screening of compounds for Ca2+ influx inhibition. • Homology Modeling and Molecular docking studies. [ABSTRACT FROM AUTHOR]

Pure, solvent-free Zn(N3)2 was prepared by reaction of diethyl zinc and hydrazoic acid in aprotic solvents. The single-crystal structure determination, along with the comprehensive characterization of α-Zn(N3)2 and two metastable polymorphs, could be achieved for the first time. Since these data disagree in large parts with the known, previously reported values, all previous syntheses of Zn(N3)2, and for comparison Zn(N3)2⋅2.5 H2O and Zn(OH)N3 were reinvestigated, indicating that some of the earlier work has to be revised. [ABSTRACT FROM AUTHOR]

The oxo tungsten(IV) alkyne complexes [Tp′W(O)(I)(η2-C2Ph2)] ( 1), [Tp′W(O)(I){η2-C2(SC2H4SiMe3)2}] ( 2), and [Tp′W(O)(I){η2-C2(SBn)2}] ( 3) [Tp′ = hydridotris(3, 5-dimethylpyrazolyl)borate, Bn = benzyl] were synthesized from [Tp′W(O)(CO)(I)]. All three compounds were fully characterized including structure determination by X-ray diffraction analysis. Further elucidation of these reactions led to the isolation of several by-products including an unexpected tungsten(IV) thioketene complex [Tp′W(O)(I){η2-S = C=C(H)(SBn)}] ( 4), which is formed by removal of one Bn group from the alkyne, and dinuclear [Tp′W(O)(I)]2(μ-O) ( 6). Both complexes were also fully characterized. X-ray diffraction analysis reveals an η2-S, C side-on binding mode for 4 and a planar O-W-O-W-O moiety for 6. In addition, by changing the solvent from THF to dichloromethane formation of the chiral dihalogen complex [Tp′W(O)(Cl)(I)] ( 5) was proven. [ABSTRACT FROM AUTHOR]

A series of thienoindolizine structural isomers have been synthesized in a one‐pot, two‐step procedure starting from easily accessible gem‐difluoroalkene functionalized bromothiophenes. The developed method gives easy access to a range of thienoindolizine products containing thieno[3,2‐g]‐, thieno[3,4‐g]‐ and thieno[2,3‐g]indolizine core structures. The described synthesis strategy consists of a base mediated, transition metal free nucleophilic substitution of fluorine atoms by nitrogen containing heterocycles followed by a Pd catalyzed intramolecular cyclization. A series of 22 final product examples has been obtained with yields ranging from 29 % to 95 %. UV/Vis absorption, fluorescence spectroscopy, fluorescence lifetime measurements and cyclic voltammetry were carried out with selected final products to evaluate structural effects on photophysical and electrochemical properties. (TD)DFT and NICS calculations were performed to provide insight into the electronic properties of the four core molecular structures. [ABSTRACT FROM AUTHOR]

Following our interest in binary element-nitrogen compounds we report here on the synthesis and comprehensive characterization (M.p., IR/Raman, elemental analysis, 14N/133Cd/199Hg NMR) of tri- and tetraazido cadmate and mercurate anions [E(N3)(2+ n)] n− (E=Cd, Hg; n=1, 2) in a series of [Ph4P]+ and [PNP]+ ([PNP]+=bis(triphenylphosphine)iminium) salts. The azide/chloride exchange in CH2Cl2 as well as the formation of tetrazolate salts in CH3CN solutions of the polyazido mercurates were investigated. Single crystal X-ray structures of all new compounds, and for comparison [Ph4P][Cd2(N3)5(H2O)], were determined. Moreover, the synthesis of anhydrous cadmium(II) azide and its DMSO adduct is presented for the first time. For a better understanding of structure and bonding in E(N3)2, [E(N3)3]− and [E(N3)4]2−, theoretical calculations at the M06-2X/aug-cc-pVDZ level were carried out. [ABSTRACT FROM AUTHOR]

The biradical [⋅P(μ‐N‐tBuPh3C)2P⋅] (6T) can be generated by reduction of a cyclic dichlorophosphane, [ClP(μ‐N‐tBuPh3C)2PCl], utilizing magnesium. If this biradical is treated with alkynes, e. g. tolan, Ph−C≡C−Ph, the addition product, a [2.1.1.] bicyclic species, [P(μ‐N‐tBuPh3C)2P(Ph−C=C−Ph)] (7), is obtained. However, if the reduction process with magnesium is carried out in the presence of tolan the reaction mixture finds a different reaction channel, ultimately yielding a magnesium(II) double salt, including a [Mg(THF)2]2+ cation with a [tBuPh3C−N−P−N−CtBuPh3]− and a novel tolan‐stabilized [(PhC=CPh)P−N−P(PhC=CPh)]− anion as counterions. This novel anion can also be conceived as anionic [2.2.1] bicycle with a [N]− ion trans‐annular bridging a 1,4‐diphosphabenzene. [ABSTRACT FROM AUTHOR]

New eydie and acylic phosphorus--nitrogen compounds have been synthesized in reactions of Hyp--N(SiMe3)PCl2 (hypersilyl = Hyp = (Me3Si)3Si) with silver salts of the perfluorinated anions [CF3C02]-, [CF3S03]-, and [C6F5]-. Depending on the choice of the silver salt, not only AgCl but also Me3SiCl elimination could be observed, leading to a transient highly reactive 1,3 dipole molecule. This 1,3 dipole molecule was found to be a key species, which can undergo [3 + 2] cydization, when a dipolarophile such as acetonitrile is present Also, dimerization or even cyclo-tetramerization are observed. The occurrence of different reaction channels demonstrates that the hypersilyl moiety can act as a highly reactive functional group. All new compounds have been characterized by single-crystal X-ray diffraction studies. [ABSTRACT FROM AUTHOR]

The synthesis of 1,3-dichloro-cyclo-1,3-diphosphadiazanes [ClP(μ-NR)]2 via elimination of Me3SiCl from silylated amino(dichloro)phosphanes, R-N(SiMe3)PCl2, was studied by different synthetic protocols starting from R-N(H)SiMe3 (R = Si(SiMe3)3 = Hyp, N(SiMe3)2, Mes* = 2,4,6-tri-tert-butylphenyl, Ter = 2,4-bis(2,4,6-trimethylphenyl)phenyl, Dipp = 2,6-diisopropylphenyl, Dmp =2,6-dimethylphenyl, Ad = Adamantyl, Trityl = Ph3C, Tos = tosyl = CH3C6H4SO2, n-Oct = n-octyl, and Me3Si). A new synthetic route using trimethylsilyl-substituted amino(dichloro)phosphanes, R-N(SiMe3)PCl2, was developed to form cyclo-diphosph(III)-azanes simply by adding a mixture of RfOH/base (RfOH = hexafluoroisopropanole). By this method electron-rich/-poor aryl-, silyl-, and bissilylamino-substituted cyclo-diphosph(III)-azanes are accessible such as the unprecedented (Me3Si)2N-substituted species [ClP(μ-NN(SiMe3)2)]2 starting from tris(trimethylsilyl)hydrazine and PCl3. Additionally, the difficulties with the preparation of cyclo-diphosphadiazanes depending on the starting materials, solvents, and bases due to the competition of different reaction channels are studied. [ABSTRACT FROM AUTHOR]

Redox‐active tungsten alkyne complex‐based phosphines of the type [Tp*W(CO)Br(η2‐C2(PR2)x] (x=1, 2; R=Ph, i‐Pr) and coordination experiments with the corresponding diphosphines are described. The pKB values of the terminal free phosphine groups were estimated indirectly by the 1JP/Se coupling constants in the associated P‐selenides. A ten orders of magnitude higher basicity for the bis(diisopropyl)phosphine derivatives compared to the diphenyl congener as well as a significant difference in basicity of the phosphine depending on its position at the alkyne was determined. The diphosphines were utilized for comparative coordination experiments with Ni(II) and Cu(I) as first row transition metals. The heterobimetallic complexes {[Tp*W(CO)Br(μ‐η2‐C,C′‐κ2‐P,P′‐C2(PR2)2]NiCl2} (R=Ph, i‐Pr) were synthesized and fully characterized, the large difference in basicity and donor strength being underlined by a different degree of stability. Furthermore, two Cu(I) complexes of the isopropyl diphosphine derivative are presented and discussed; one of both being a dinuclear phenanthroline Cu(I) complex and the other a tetranuclear complex exhibiting an angled Cu2Br+ core. [ABSTRACT FROM AUTHOR]

Abstract: Highly functionalized ferrocenyl-substituted phenols were prepared by cyclization of masked or free dianions with 1,3-dielectrophilic 1-η5-ferrocenyl-3,3-bis(methylthio)prop-2-en-1-ones. While the cyclizations of 1,3-bis(silyloxy)-1,3-butadienes (masked dianions) proceed by initial 1,2-addition, the reactions of free 1,3-dicarbonyl dianions proceed by initial 1,4-addition. Therefore, both regioisomeric ferrocenylphenols are available from one and the same electrophile dependent on the type of nucleophile and reaction conditions employed. The reactions reported represent the first examples of the application of formal [3 + 3] cyclizations to the synthesis of organometallic compounds. [Copyright &y& Elsevier]

Differently substituted hydrazinophosphanes of the type (Me3Si)2N−N(SiMe3)−PR1R2 (R1 = Cl with R2 = Me, C6F5 and R1 = Me, R2 = C6H5) have been studied in the reaction with Lewis acids such as ECl3 (E = Al, Ga). For (Me3Si)2N−N(SiMe3)−P(Cl)(Me) and (Me3Si)2N−N(SiMe3)−P(Me)(C6H5), only adduct formation was found while a chlorine/methyl exchange reaction was observed for (Me3Si)2N−N(SiMe3)−P(Cl)R (R = C6H5 and C6F5) leading to the formation of (Me2ClSi)(Me3Si)N−N(SiMe3)−P(Me)R, which crystallize as ECl3 adducts. The free hydrazinophosphanes can be obtained by removal of the Lewis acid with the help of a strong base such as 4-(dimethylamino)pyridine (DMAP). [ABSTRACT FROM AUTHOR]

The reaction of m-terphenyl amine (2,6-bis-(2,4,6-trimethylphenyl)aniline, m-Ter = m-terphenyl = 2,6-bis-(2,4,6-trimethylphenyl)) and ECl3(E = P, As) in the presence of different bases (Et3N, n-BuLi, LDA, DBU) and under different reaction conditions was studied. The reaction with excess Et3N yielded m-Ter–N(H)–AsCl2for E = As, while for E = P m-Ter–N(PCl2)2was formed. m-Ter–N(H)–ECl2was obtained in the reaction of m-terphenyl amine with n-BuLi and ECl3for E = As and P. Further treatment of m-Ter–N(H)–PCl2with Et3N led to the formation of 1,3-dichloro-cyclo-1,3-diphospha-2,4-diazane, a synthesis protocol which cannot be applied to the analogous arsenic species. 1,3-dichloro-cyclo-1,3-diarsa-2,4-diazane was isolated when DBU was added to m-Ter–N(H)–AsCl2at low temperature (−80 °C). [ABSTRACT FROM AUTHOR]

1,2-Diarylanthraquinones were prepared by Suzuki-Miyaura reactions of the bis(triflate) of 1,2-dihydroxyanthraquin�one (alizarin). The reactions proceed with excellent site selectivity. The first attack occurs at the sterically more hindered position 1, due to electronic reasons. [ABSTRACT FROM AUTHOR]

The first Suzuki-Miyaura reactions of 2,3,5-tribromothiophene are reported. These reactions provide a convenient and site-selective approach to 5-aryl-2,3-dibromothiophenes, 2,5-diaryl-3-bromothiophenes, and 2,3,5-triarylthiophenes. [ABSTRACT FROM AUTHOR]

A series of different cyclo-diarsa-diazenium salts bearing several bulky groups such as supermesityl (Mes* = 2,4,6-tBu3C6H2) and m-terphenyl (2,6-Mes2-C6H3, Mes = 2,4,6-Me3C6H2) and anions such as triflate (OTf = SO3CF3 = trifluoromethylsulfonate) and tetrachloridogallate (GaCl4-) were synthesized and fully characterized. The novel 1-chloro-cyclo-1,3-diarsa-2,4-diazenium cation represents the first example of a binary cyclic As(III)/N four-membered heterocyclic, with a di- and tricoordinated As atom and a delocalized π bond along the NAs(+)N unit. The addition of excess Me3SiN3 yields the fully characterized cationic arsenic azide, 1-azido-cyclo-1,3-diarsa-2,4-diazenium-μ-azido-hexachlorido-digallate. The Cl-/N3- exchange is triggered by the action of the Lewis acid GaCl3. Depending on the Me3SiN3 stoichiometry, different μ-azido-hexachlorido-digallate salts with either 1-chloro- or 1-azido-cyclo-1,3-diarsa-2,4-diazenium cations or even a mixture of both are observed. Moreover, it was of special interest to study the distances between the cationic arsenic center and anion in cyclo-diarsa-diazenium salts. A correlation between the color of the salt and the anion/cation distance, ranging between 2 and 8 Å in cyclo-diarsa-diazenium salts of the type [R2N2As2Y]+X- depending on the bulky group R (R = Mes*, Ter), the substituent Y (Y = Cl, N3, OTf), and the anion X- (X = OTf, GaCl4, Cl3Ga—N3—GaCl3), was established. [ABSTRACT FROM AUTHOR]

The preparative access to and first group 10 metal complexes of novel 1H-1,2,3-triazole-4,5-dithiolate ligands (tazdt2−) are reported. A set of S-protected 1H-1,2,3-triazole-4,5-dithiol derivatives with R1 = 2,6-dimethylphenyl (Xy) or benzyl (Bn) at N1 and with R2 = Bn or trimethylsilylethyl (TMS-ethyl) at both S atoms were synthesized by a 1,3-dipolar cycloaddition catalysed by either Ru(II) or Cu(I). Extensive investigations on the removal of the protective groups resulted the reductive removal of benzyl groups to be superior in isolating the free 4,5-dithiols of R1N3C2(SH)2 with R1 = Xy (H2-8) or Bn (H2-9). Coordination of these ligands led to the formation of the metal complexes [(η5-C5H5)2Ti(8)], [Ni(dppe)(8)], [Ni(dppe)(9)], [Pd(dppe)(9)] {dppe = bis(diphenylphosphanyl)ethane} and homoleptic (NBu4)n[Ni(8)2] (n = 1, 2). All complexes were fully characterized including structure determination by single crystal XRD. The electronic properties of the Ni and Pd complexes were determined by cyclic voltammetry, UV/vis and EPR spectroscopy supported by DFT calculations. According to the spectral and electrochemical data, the tazdt2− complexes resemble the corresponding benzene-1,2-dithiolate (bdt2−) type compounds reflecting the restricted influence of the electron-withdrawing N3 moiety in the backbone. DSC-TGA measurements with [(η5-C5H5)2Ti(8)] and [Ni(dppe)(8)] indicate a well-defined thermal process involving simultaneous elimination of both N2 and CS. [ABSTRACT FROM AUTHOR]

The authors of this work have optimized a novel synthetic route towards glucose‐based PdII‐bis(NHC) complexes in only 4 steps with total yields up to 73 %. The synthesis route encompasses an Appel reaction towards 6‐iodo‐glucopyranosides, followed by acyl‐protection, then quaternization with imidazoles and finally the conversion of these acyl‐protected glucosyl imidazolium salts to their respective palladium(II)bis(NHC) complexes, via an intermediary silver(I) complex. Overall, 11 acyl‐protected glucosyl imidazolium iodides as NHC‐precursors and 15 complexes have been synthesized. The structure‐activity relationships of different functionalizations in these complexes and their reactivity in a model Suzuki‐Miyaura between bromobenzene and 4‐tolueneboronic acid reaction has been investigated, and a highly reactive complex leading to >99 % yield at 0.005 mol% catalytic loading has been found. [ABSTRACT FROM AUTHOR]

Finally isolated: The isolation of a nitridophosphane(V) was described for the first time by the research group of Bertrand. The reactivity and the possibility of stabilizing labile R2PN/R2NP species (see structure) are discussed. [ABSTRACT FROM AUTHOR]

Endlich isoliert: Ausgehend von einem Beitrag der Arbeitsgruppe Bertrand, in dem die erstmalige Isolierung eines Nitridophosphans(V) beschrieben wird, werden die Reaktivität und die Möglichkeiten der Stabilisierung von labilen R2PN/R2NP ‐ Spezies (siehe Strukturformeln) diskutiert. [ABSTRACT FROM AUTHOR]

Hypersilyl(trimethylsilyl)aminodichlorophosphine, (hyp)N(SiMe3)PCl2, was treated with GaCl3, which resulted in the formation of an interesting novel bicycle, composed of a four-membered SiNP2 ring and a five-membered P2Ga2Cl ring. In the presence of Me3SiN3, the same reaction provided access to a cyclo-2-phospha-4-sila-1,3-diazenium tetrachlorogallate. The free chloro-cyclo-phosphasiladiazane was obtained by the addition of nucleophilic bases. [ABSTRACT FROM AUTHOR]

N‐Benzyl‐ and N‐2°‐alkylpyridinium salts were engaged in visible‐light‐driven, photoredox‐induced radical‐cationic three‐component couplings with N‐methylmaleimide and acrylonitrile as radical acceptors, in combination with 1,1‐diarylethylenes as donor alkenes. These multicomponent coupling reactions could be achieved under mild conditions, with high efficiency, and to furnish diverse 3,4‐disubstituted pyrrolidin‐2,5‐dione products with high stereoselectivity. In addition, 2,3‐diaryl‐1,3‐butadienes could be utilized as alternative donor alkene components, to furnish diastereomerically pure 1,2,3‐trisubstituted 1,3‐butadienes as the coupling products. [ABSTRACT FROM AUTHOR]

The C10a‐acetoxylated tetrahydroazepino[1,2‐a]indole‐6,11‐diones are a class of tricyclic oxindoles that feature an α‐keto‐N,O‐acetal substructure, rendering them highly susceptible to SET reduction followed by fragmentation. In protic medium, they undergo a PCET‐assisted two‐step reduction including an interposed C−O bond cleavage that can be initiated photocatalytically as well as by cathodic reduction, and which generates nucleophilic ketyl radicals. In the presence of acrylonitrile and DIPEA as additional reactants, the photoinduced reaction unfolds as a tandem C−O bond reduction/ketyl radical conjugate addition, to furnish C10a‐reduced, C11‐cyanoethyl‐substituted tricyclic azepino‐[1,2‐a]indole derivatives with high stereoselectivity. [ABSTRACT FROM AUTHOR]

Phosphor‐zentrierte Disbiradikale, in denen die Radikalzentren als einzelne Spin‐Dubletts mit schwacher Spin‐Spin‐Wechselwirkung vorliegen, waren bisher nicht bekannt. Ausgehend von Monoradikalen des Typs [⋅P(μ‐NTer)2P−R] ist es uns nun gelungen, zwei monoradikalische Phosphorzentren durch geeignete Wahl eines Linkers zu verknüpfen. Zu diesem Zweck wurde das Biradikal [⋅P(μ‐NTer)2P⋅] (1) mit 1,6‐Dibromhexan umgesetzt, wodurch die bromierte Spezies {Br[P(μ‐NTer)]2}2C6H12 (3) entstand. Die anschließende Reduktion mit KC8 führte zur Bildung des Disbiradikals {⋅[P(μ‐NTer)]2}2C6H12 (4), das sich durch einen großen Abstand zwischen den radikalischen Phosphorzentren im Festkörper auszeichnet und mit annähernd 100 % den bisher höchsten Biradikalcharakter in einem P‐zentrierten Biradikal aufweist. Die EPR‐spektroskopische Untersuchung ergab ein Drei‐Linien‐Signal in Lösung mit einer erheblich größeren Austauschwechselwirkung als es aufgrund der Molekülstruktur im Einkristall zu erwarten wäre. Quantenchemische Berechnungen ergaben einen hochdynamischen Konformationsraum; demnach können sich die beiden Radikalstellen in Lösung mit einem viel geringeren Abstand einander nähern. Die weitere Reduktion von 4 führte zur Bildung eines Kaliumsalzes mit dem ersten strukturell charakterisierten P‐zentrierten distonischen Radikalanion (5−). Außerdem konnte 4 für die Aktivierung kleiner Moleküle eingesetzt werden. [ABSTRACT FROM AUTHOR]

Phosphorus‐centered disbiradicals, in which the radical sites exist as individual spin doublets with weak spin‐spin interaction have not been known so far. Starting from monoradicals of the type [⋅P(μ‐NTer)2P−R], we have now succeeded in linking two such monoradical phosphorus centers by appropriate choice of a linker. To this end, biradical [⋅P(μ‐NTer)2P⋅] (1) was treated with 1,6‐dibromohexane, affording the brominated species {Br[P(μ‐NTer)]2}2C6H12 (3). Subsequent reduction with KC8 led to the formation of the disbiradical {⋅[P(μ‐NTer)]2}2C6H12 (4) featuring a large distance between the radical phosphorus sites in the solid state and formally the highest biradical character observed in a P‐centered biradical so far, approaching 100 %. EPR spectroscopy revealed a three‐line signal in solution with a considerably larger exchange interaction than would be expected from the molecular structure of the single crystal. Quantum chemical calculations revealed a highly dynamic conformational space; thus, the two radical sites can approach each other with a much smaller distance in solution. Further reduction of 4 resulted in the formation of a potassium salt featuring the first structurally characterized P‐centered distonic radical anion (5−). Moreover, 4 could be used in small molecule activation. [ABSTRACT FROM AUTHOR]

Reactions of a masked N‐heterocyclic phosphinidene (mNHP, 1), a four‐membered heterocycle with a divalent P atom, with various isonitriles (tBu−NC, Dmp−NC) and carbonyls (CO, Fe(CO)5, and benzalacetone) have been studied. The isonitriles (tBu−NC and Dmp−NC) insert into a P−N bond of the four‐membered ring of 1, leading to the formation of a five‐membered heterocycle (2tBu, 2Dmp), indicating carbene‐like reactivity of the isonitriles. In exactly this way, CO, which is isolobal to isonitriles, reacts to form a five‐membered ring (3) with an exocyclic C=O double bond. If, on the other hand, Fe(CO)5 is used as a CO source, a CO molecule is inserted analogously, however, the remaining Fe(CO)4 fragment is bound via a phosphorus‐iron dative bond to the five‐membered heterocycle. When mNHP 1 reacts with the α,β‐unsaturated ketone benzalacetone, phosphinidene reactivity is observed for 1. This means that the four‐membered ring opens and the P atom reacts with the benzalacetone in a cyclization reaction to form a 1,2‐oxaphospha‐cyclopentene. Theoretical studies of the five‐membered heterocycles 2 and 3 carrying eight π electrons show that zwitterionic Lewis representations dominate in the resonance scheme and only a very low biradical character (<5 %) is found. [ABSTRACT FROM AUTHOR]

2‐(1‐Hydroxyethylidene)malononitrile (4) is commercially sold as the keto isomer and is described in the literature as either a keto (4 b) or enol (4 a) species. Using NMR techniques and single crystal X‐ray diffraction, we were able to show that 4 exists exclusively as the enol isomer (4 a) in solution as well as in the solid state, which agrees with quantum chemical calculations. By adding one or two equivalents of the Lewis acid B(C6F5)3, the mono‐ or diadducts are formed in exergonic reactions, in which the enol form is further thermodynamically stabilized. The structure and acidity of enol 4 a and its borane adducts are discussed based on experimental and theoretical results. [ABSTRACT FROM AUTHOR]

A concise and modular synthesis of pyrrolo[1,2- a ][1,6]- and [1,8]naphthyridines by a one-pot two-step reaction consisting of electrophilic acylation followed by an alkyne-carbonyl-metathesis reaction as the final cyclization step is reported. This developed synthetic methodology allows the facile synthesis of these heterocyclic core structures in mainly high overall yields under metal-free conditions. Reaction conditions are carefully optimized and display a novel supplement to access these tricyclic heterocyclic compounds. [ABSTRACT FROM AUTHOR]

The incorporation of heteroatoms into polycyclic aromatic hydrocarbons (PAHs) has been recognized as valuable tool to alter their inherent optical and electrochemical properties and are thought as promising next‐generation semiconductor materials. We herein report the synthesis of diindenopyrene, a fragment of C70 and two of its nitrogen‐doped aza‐analogs. The developed synthetic procedure is based on Brønsted‐acid‐mediated cycloisomerization followed by Pd‐catalyzed C−H‐activation as key‐steps. The impact of N‐doping on the optical and electrochemical properties has been studied and the experimental results are supported by DFT calculations. [ABSTRACT FROM AUTHOR]

A convenient three‐step synthesis of dibenzo[a,j]acridines is reported which relies on regioselective Pd‐catalyzed cross‐coupling reactions of 2,3,5,6‐tetrachloropyridine and subsequent Brønsted acid mediated cycloisomerization. Products are obtained in good yields and the method is broadly applicable. For selected dibenzo[a,j]acridines, photophysical and electrochemical properties were studied. [ABSTRACT FROM AUTHOR]

The reaction of biradical [P(μ‐NTer)]2 (1, Ter = 2,6‐bis(2,4,6‐trimethylphenyl)phenyl) towards different alkenes (R = 2,3‐dimethyl–butadiene, 2,5‐dimethyl‐2,4‐hexadiene, 1,7‐octadiene, 1,4‐cyclohexadiene) and alkynes (R = 1,4‐diphenyl‐1,3‐butadiyne) was studied experimentally. Although these olefins can react in different ways, only [2+2] cycloaddition products (1R) were observed. The reaction with 2,3‐dimethylbutadiene also led to the [2+2] product (1dmb). Thermal treatment of 1dmb above 140 °C resulted in the recovery of biradical 1 upon homolytic bond cleavage of the two P–C bonds and the release of 2,3‐dimethylbutadiene. In contrast to this reaction, all other [2+2] additions products (1R, R = 1,7‐octadiene, 1,4‐cyclohexadiene, 1,4‐diphenyl‐1,3‐butadiyne) began to decompose at temperatures between 200 °C and 300 °C. Only unidentified products were obtained but no temperature‐controlled equilibrium reactions were observed. Computations were carried out to shed light into the formal [2+2] as well as the possible [4+2] addition reaction. [ABSTRACT FROM AUTHOR]

A variety of thienoquinolones were synthesized from readily accessible thiophene derivatives by regioselective acylations and subsequent two‐fold Buchwald–Hartwig–amination. This cyclization allows a convenient synthesis of biologically and pharmaceutically important thienoquinolones. Several thienoquinolones were synthesized in good to very good yields. The optical properties of the products were studied in detail. [ABSTRACT FROM AUTHOR]

Various tin(ii) compounds such as Mes*2Sn (Mes* = 2,4,6-tri-tert-butylphenyl), Sn[N(SiMe3)2]2 and TerSnCl (Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl) could be readily oxidised by organic azides to release N2, forming nitrogen-tin compounds. Depending on the used Sn(ii) compound, the reactions with two equivalents of azide led to the formation of tetrazastannoles (R2N4SnR′2) or cyclo-distannadiazanes [R2Sn(μ-NR′)]2. The reactivity was independent of the electronic situation of the organic azide. Additionally, Mes*2Sn formed an amido-azido compound of the type R(R′)Sn(N(SiMe3)2)N3 in the presence of Me3SiN3. Presumably, the corresponding tetrazastannole was formed in the first step followed by a ring opening reaction. The same holds true for the reaction of Sn[N(SiMe3)2]2 with Me3SiN3 while TerSnCl showed no reaction in the presence of Me3SiN3, even after prolonged heating. [ABSTRACT FROM AUTHOR]

Halide addition and abstraction experiments with the cationic rhenacyclopentatriene [(η5‐C5H5){ReC4(SBn)4}Br]BF4 and the side‐on cyclobutadiene complexes [(η5‐C5H5)(η4‐C4Ph4)ReX2] (X = Br, I), respectively, are described. Reversible interconversion of both coordination modes of the metal bonded C4R4 moiety depending on the presence or absence of the second bromide ligand is demonstrated for the sulfide derivative. However, formation of the [(η5‐C5H5)(ReC4Ph4)X]+ congener by halide abstraction at [(η5‐C5H5)(η4‐C4Ph4)ReX2] turned out to be impossible. Instead, formation of silver halide complexes with the halide bridging rhenium and silver under retention of the metalorganic scaffold are observed. Governed by the phenyl substituent framework a square‐planar coordination environment about the Ag cation is adopted for X = Br. Changing X = Br by X = I led to the formation of a heptanuclear complex with di‐ and three‐coordinate silver ions. [ABSTRACT FROM AUTHOR]

α-Zn(N3)2 (I) is prepared by addition of ethereal HN3 to a solution of ZnEt2 in hexane at 0 °C (90-95% yield; caution, covalent azides can explode violently). [ABSTRACT FROM AUTHOR]

Differently substituted phenyl isonitriles (with C−H bonds in ortho‐position) and naphthyl isonitriles were reacted with the cyclic biradical [⋅P(μ‐N‐Ter)2P⋅] (1). Insertion of the isonitrile formed a cyclic five‐membered biradical [⋅P(NTer)2C(R)P⋅] (2R, R=phenyl, naphthyl) in the first step, followed by C−H activation at the aryl substituent, resulting in novel azaphospholes (5R), which could be isolated and fully characterized. The formation of the azaphospholes can be prevented by the addition of a second equivalent of isonitrile, which causes the blocking of the radical centers in 2R by adduct formation (3R). Quantum mechanical calculations showed that a significant increase in the aromaticity of the benzo‐ and naphtho‐azaphospholes is one of the driving forces for the activation process leading to the formation of thermodynamically favored azaphospholes. Targeted activation of C−H bonds using biradical systems represents a new synthetic approach to generate benzo‐ and naphtho‐azaphospholes. [ABSTRACT FROM AUTHOR]

We present the extension of Pacman ligands to bidentate phosphane ligands enabling them to bind metals in their sterically protected cavity. The coordination of coinage metals shows the ability of the ligand to adopt different coordination modes by distortion, of which some additionally include the imine nitrogen atoms. Besides the coordinated metal, the substitution on the phosphorus atoms influences the type of coordination. [ABSTRACT FROM AUTHOR]