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Methyl or ethyl 3‐nitropropenoates (β‐nitroacrylates) AlkO(O)C1−C2H=C3H−NO2 in reaction with arenes ArH in triflic acid CF3SO3H (TfOH) at room temperature in 1 h give rise to oximes of alkyl 2,3‐diaryl‐3‐oxopropanoates AlkO(O)C−CH(Ar)−C(Ar)=NOH in yields of 42–92 %. The obtained oximes bearing ortho‐methyl substituents in the aryl ring exist as atropoisomers in solutions. The study of protonated forms of β‐nitroacrylates by NMR and DFT calculations has revealed that the reactive electrophiles are species AlkO(HO+)C1−C2H=C3H−N+(O)(OH) protosolvated on the acceptor groups NO2 and CO2R. Plausible reaction mechanism is based on the primary interaction of aromatic nucleophiles with these electrophilic species onto their carbon C2. [ABSTRACT FROM AUTHOR]

Trimethylsilyl ethers of trifluoromethyl substituted benzyl type alcohols of thiophene and (benzo)furan series undergo multichannel electrophilic transformations in triflic acid CF3SO3H (TfOH). Intermediate cationic species generated from starting heterocycles interact with arenes, leading to the formation of various products of side chain arylation, dehalogenation, arylation of the heteroaromatic core, intramolecular cyclization, hydro-detrimethylsilylogenation, oxo-dehalogenation, and others. The reaction pathway depends on the structure of an intermediate cation, nucleophilicity of the arene, reaction time, and temperature. Plausible mechanisms of these electrophilic reactions are discussed. The obtained trifluoromethyl substituted compounds exhibit good antimicrobial activity against Candida albicans, a yeast-like fungus, at concentrations ranging from 64 to 128 μg mL−1 and inhibit the growth of both Escherichia coli and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

[Display omitted] Reactions of 3-arylpropynoic acid derivatives and conjugated acetylene ketones with arenes and cyclohexane under the action of AlCl 3 at room temperature for 15 h afford the corresponding products of one-pot tandem hydroarylation–ionic hydrogenation of the acetylene bond of the starting compounds in 42–98% yields. This reaction is accompanied by aryl group exchange process under acidic conditions. [ABSTRACT FROM AUTHOR]

Solid state structures of five new molecular complexes of SbI3 with Py have been determined by single crystal X-ray structural analysis. In all complexes, all antimony atoms adopt a pseudooctahedral coordination geometry, which is completed by additional Sb···I contacts shorter than sum of van der Waals radii, with I- Sb···I angles close to 180°. Analysis of the electrostatic potentials, the orbital interactions and topological analysis indicate that these contacts are due to the presence of Sb···I pnictogen bonds. The first example of three pnictogen bonds of SbI3 is reported. [ABSTRACT FROM AUTHOR]

The cover picture symbolically shows formation of three pnictogen bonds by the antimony triiodide molecule, which is depicted as the three‐headed dragon Zmey Gorynych. The heads of the dragon represent iodine atoms and the tails of the dragon – positively charged regions of antimony atom. Neighboring iodine atoms “bite” all three tails to form three pnictogen bonds at one antimone center. The coloring of the Zmey Gorynych corresponds to the electrostatic potential (ESP) mapped on the molecular surface, ranging from red (negative) to blue (positive). Three small objects show ESP plot of SbI3 molecule. More details can be found in the Article by Alexey Y. Timoshkin et al. [ABSTRACT FROM AUTHOR]

A high-yielding method for the synthesis of 2 H -1,3,5-oxadiazines by rhodium(II)- or copper(II)-catalyzed reaction of 1,2,4-oxadiazoles with α-diazo esters has been developed. The reaction proceeds via attack of the metallocarbenoid on the oxadiazole N2 atom followed by ring opening/1,6-electrocyclization and enables the introduction of alkyl, aryl, oxy, and amino substituents into the 6-position and electron-withdrawing groups into the 2-position of 1,3,5-oxadiazine. The N2-attack and the N4-attack of the carbenoid cause different oxadiazole ring openings, which are controlled by the substitution at C5. The presence of a substituent at this position is a prerequisite for the N2-attack to occur, leading to the formation of 1,3,5-oxadiazines. [ABSTRACT FROM AUTHOR]

Reactions of linear conjugated dienone structures ArCH＝CHCH＝CHC(＝O)X, 1,5-diarylpenta-2,4-dien-1-ones (X = Ar′), 5-phenylpenta-2,4-dienoic acid (Ar = Ph, X = OH) and its methyl ester (Ar = Ph, X = OMe), with arenes under superelectrophilic activation conditions by Brønsted superacids (CF3SO3H and FSO3H) or strong Lewis acid (AlCl3) result in the formation of various compounds, such as conjugated enones, indanes, and carbocyclic derivatives. The formation of the reaction products depends on the structures of starting compounds (dienone and arene) and on the reaction conditions (temperature, time, and medium acidity). In these transformations, starting dienones are precursors of di- and tri-centered electrophilic synthons leading to target products. A NMR study and DFT calculations have shown that the most probable reactive intermediates should be O,C-diprotonated species Ar+CHCH2CH＝CHC(＝O+H)X derived from the protonation of starting dienones. Plausible mechanisms of electrophilic transformations are discussed. [ABSTRACT FROM AUTHOR]

The multi-component 1,3-dipolar cycloaddition of ninhydrin, α-amino acids (or peptides), and cyclopropenes for the synthesis of spirocyclic heterocycles containing both 3-azabicyclo[3.1.0]hexane and 2 H -indene-1,3-dione motifs has been developed. This method provides easy access to 3-azabicyclo[3.1.0]hexane-2,2′-indenes with complete stereoselectivity and a high degree of atom economy under mild reaction conditions. A broad range of cyclopropenes and α-amino acids have been found to be compatible with the present protocol, which offers an opportunity to create a new library of biologically significant scaffold (3-azabicyclo[3.1.0]hexane). In addition, the сomprehensive study of mechanism of azomethine ylide formation from ninhydrin and sarcosine was performed by means of M11 density functional theory (DFT) calculations. It has been revealed that experimentally observed 1-methylspiro[aziridine-2,2′-indene]-1′,3′-dione is a kinetically controlled product of this reaction and appears to act as a 1,3-dipole precursor. This theoretical study also shed light on the main transformations of the azomethine ylide derived from ninhydrin and sarcosine such as a 1,3-dipolar cycloaddition to cyclopropene dipolarophiles, a dimerization reaction and a (1+5) electrocyclization reaction. The antitumor activity of some synthesized compounds against cervical carcinoma (HeLa-) cell line was evaluated in vitro by MTS-assay. [ABSTRACT FROM AUTHOR]

Linear-conjugated enynones,1,5-diarylpent-4-en-2-yn-1-ones [Ar2􀀀 CH=CH􀀀 C�C􀀀 C(=O)Ar1], have been cyclized into 2,6-diaryl-2,3-dihydropyran-4-ones in triflic acid TfOH (CF3SO3H). Reactions of these enynones with arenes Ar3H in TfOH have afforded, at first stage, products of hydroarylation of the acetylene bond, 1,3,5-triarylpent-2,4-dien-1-ones [Ar2􀀀 CH=CH􀀀 C(Ar3)=CH􀀀 C(=O)Ar1], which have been further cyclized into alkylidene indanes. Plausible reaction mechanisms have been proposed. According to quantum chemical calculations by DFT method, initial key reactive intermediates are vinyl type dications [Ar2􀀀 CH=CH􀀀 C+=CH􀀀 C(=O+H)Ar1], generated under the protonation of carbonyl oxygen and acetylene bond of starting enynones in TfOH. [ABSTRACT FROM AUTHOR]

A new convenient approach to the synthesis of useful N-heterocyclic carbene complexes of group 13 metals was successfully developed. We demonstrate that air-stable copper(I) diaminocarbene complexes are excellent carbene transfer reagents for the synthesis of (IMes or IPr)MCl3 with high yields (M = Al, Ga). Use of this simple method allowed for the first time to obtain (IPr)AlCl3, inaccessible via a free carbene route. In contrast to copper complexes, under the same conditions the more commonly used silver analog (IPr)AgCl reacts with MCl3 (M = Al, Ga, In) yielding only the homoleptic cationic complexes [(IPr)2Ag]+MCl4−. [ABSTRACT FROM AUTHOR]

• Bifurcated N H⋯Cl noncovalent contacts were observed in the crystal structure. • The estimated energy of these interactions is 5.2–7.6 kcal/mol per each associate. • The complexes exhibit emission maxima in the range 372–422 nm and ns lifetimes. Five bis-triazole zinc(II) chloride complexes exhibiting solid-state fluorescence were prepared in 58–99% isolated yields and fully characterized by HRESI-MS, IR, 1H- and CP-MAS TOSS 13C{1H} NMR. Results of single-crystal XRD indicate that their crystal structures include the rare bifurcated N H⋯Cl noncovalent contacts. The estimated energy of these interactions is 1.3–1.9 kcal/mol (5.2–7.6 kcal/mol per each associate) as verified by DFT calculations at the ωB97XD/6-31G(d) level of theory and by QTAIM method. The complexes exhibit emission maxima in the range 372–422 nm and nanosecond lifetimes of the fluorescence. In the case of the 3-pheny-1-dimethylamino-1,2,4-triazole complex, a significant enhancement of quantum yield (ca. 20-fold) and blue shift of the emission maximum (33 nm) were observed relatively to the uncomplexed 1,2,4-triazole. [ABSTRACT FROM AUTHOR]

• Synthesis of the rare PdII osazone complex. • Self-assembly of the new complex into lasagna-like arrays in the solid state via C (sp2)–H⋯Hal hydrogen bonding. • X-ray diffraction analysis of the new material. • Theoretical study of the nature and energies of intermolecular non-covalent interactions. Preparation of the novel PdII osazone complex and its self-assembly into lasagna-like arrays in the solid state via rare C(sp2)–H⋯Hal hydrogen bonding, as well as N–H⋯Ph weak contact is reported. The rare PdII osazone complex was characterized using elemental analyses (C, H, N), ESI-MS, IR, 1H and 13C NMR techniques and X-ray diffraction analysis. The intermolecular non-covalent interactions C–H⋯Cl and N–H⋯Ph responsible for the formation of 1D supramolecular polymeric chains in the crystal were detected and studied by DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method). Estimated strength of these non-covalent interactions is 1.3–1.6 kcal/mol. [ABSTRACT FROM AUTHOR]

Complexes formed by interaction of E(C6F5)3 (E = B, Al, Ga, In) with excess of acetonitrile (AN) were structurally characterized. Quantum chemical computations indicate that for Al(C6F5)3 and In(C6F5)3 the formation of a complex of 1:2 composition is more advantageous than for B(C6F5)3 and Ga(C6F5)3, in line with experimental observations. Formation of the solvate [Al(C6F5)3·2AN]·AN is in agreement with predicted thermodynamic instability of [Al(C6F5)3·3AN]. Tensimetry study of B(C6F5)3·CH3CN reveals its stability in the solid state up to 197 °C. With the temperature increase, the complex undergoes irreversible thermal decomposition with pentafluorobenzene formation. [ABSTRACT FROM AUTHOR]

A catalytic nucleophilic addition reaction of 3‐hydroxybenzofuran‐2‐carboxylic acid derivatives to 2H‐azirines for the high‐yield synthesis of NH‐aziridines with a 3‐coumaranone substituent has been developed. The Ph3PAuNTf2‐catalyzed reaction is diastereoselective to give predominantly (RS,SR)‐isomer of aziridine in good yield. The Ni(hfacac)2‐catalyzed reaction affords aziridines in up to 98% yield and low or moderate diastereoselectivity, which in some cases is opposite to that observed for the gold(I)‐catalyzed reaction. The Ph3PAuNTf2 works well for sterically hindered azirines as well as benzofurans bearing electron‐withdrawing groups, whereas Ni(hfacac)2 is the catalyst of choice for the preparation of aziridines having diazoacetyl substituent. The latter compounds can serve as substrates for the synthesis of fused aziridines via Buchner ring expansion reaction. [ABSTRACT FROM AUTHOR]

The first zwitterions with [NHN]+ and [NHN]− intramolecular hydrogen bonds have been studied. Due to their mutual reinforcement, shortening of N…N distances in both NHN subunits (up to 2.546 Å) occurs in symmetrical zwitterion 12. Being less acidic, the [NHN]− bridge makes the [NHN]+ part harder to disrupt, thus rendering 12 superbasic and recognition properties. [ABSTRACT FROM AUTHOR]

Trimethylsilyl ethers of 1,5-diaryl-3-(trifluoromethyl)pent-1-en-4-yn-3-oles in superacid CF3SO3H (TfOH) give rise to the corresponding intermediate CF3-pentenynyl cations. These species react with benzene to afford conjugated CF3-pentenynes, which undergo subsequent cyclization, first, into CF3-cycloheptadienes and, finally, into unusual CF3-“helicopter”-like bicyclic structures. [ABSTRACT FROM AUTHOR]

A systematic structural study of complexes formed by aluminium and gallium trihalides with 4,4′-bipyridine (bipy) in 2 : 1, 1 : 1, and 1 : 2 stoichiometric ratios has been performed. Molecular structures of 11 complexes in the solid state have been determined for the first time. Complexes of 2 : 1 composition are molecular, while complexes of 1 : 1 composition form metal–organic frameworks of different kinds: an ionic 3D network (three interpenetrated lvt nets for AlCl3bipy), an ionic 2D network for AlBr3bipy and GaBr3bipy and a 1D coordination polymer in the case of GaCl3bipy. Thus, the nature of the Lewis acid plays a critical role in the structural type of the complex in the solid state. Incorporation of excess bipy molecules into (GaCl3bipy)∞ (formation of crystallosolvate) leads to an unprecedented change of the molecular structure from a non-ionic 1D coordination polymer to an ionic 2D metal organic framework [GaCl2bipy2]+[GaCl4]−·2bipy. As indicated by the temperature-dependent XRD study, removal of bipy by heating in a vacuum restores the non-ionic 1D structure. Quantum chemical computations for simple cluster model systems (up to eight Al and Ga atoms) reveal that ionic forms are slightly favourable, although the energy differences between the ionic and non-ionic structures are not large. These theoretical predictions are in good agreement with experimental findings. Thus, even relatively simple cluster models may be used to indicate the structural preferences in the solid state. Both experimental and computational IR frequency shifts of the in-plane ring bending mode of bipy upon complexation correlate well with the M–N bond distances in the complexes. [ABSTRACT FROM AUTHOR]

Reaction of organoiridium(III)-2-phenylpyridine complex, [Ir(ppy) 2 ( μ -Cl)] 2 (ppy = 2-phenylpyridinato- C 2 , N ), with 4-(2-bromophenyl)-1,2,3-thiodiazole (X) or 4-(2-bromophenyl)-1,2,3-selenadiazole (Y) in CH 2 Cl 2 yields to [Ir(ppy) 2 Cl(X)]·CH 2 Cl 2 ( 1 ) or [Ir(ppy) 2 Cl(Y)] ( 2 ), respectively. Both compounds were characterized by characterized by elemental analyses (C, H, N), HRESI + -MS, FTIR, and studied by single-crystal X-ray diffraction. The coordination environment of the central iridium(III) has a distorted octahedral geometry, four sites being occupied by two (ppy) − , which chelates in the C,N fashion, while the two other sites are filled with the Cl − and X (or Y) ligands. The intramolecular S ··· N and Se ··· Cl types of chalcogen bonds were found in the structures of 1 and 2 , respectively. Compound 1 is also present intramolecular pnicogen bonding and intermolecular halogen bonding (between CH 2 Cl 2 molecules) with the short N ··· Br (3.160 Å) and Cl ··· Cl (2.187 Å) distances. The crystal structures in 1 and 2 are stabilized by medium-strong intermolecular hydrogen bonding interactions. [ABSTRACT FROM AUTHOR]

• High efficient and selective synthesis of new 5-spiroisoxazolidines. • High stereoselective 1,3-dipolar cycloaddition of nitrones. • New synthetic approach to spirolactones. The 1,3-dipolar cycloaddition of keto- and aldonitrones with N -arylitaconimides proceeds regioselectively giving only 5-spiroisoxazolidines. In the case of aldonitrones the reaction proceeds with high diastereoselectivity. A range of the obtained adducts were subjected to reductive cleavage of the N O bond using zinc powder in acetic acid to give the corresponding spirolactones and 1,3-amino alcohols. [ABSTRACT FROM AUTHOR]

The TfOH-mediated reactions of 2,4-diaryl-1,1,1-trifluorobut-3-yn-2-oles (CF3-substituted diaryl propargyl alcohols) with arenes in CH2Cl2 afford 1,3-diaryl-1-CF3-indenes in yields up to 84%. This new process for synthesis of such CF3-indenes is complete at room temperature within one hour. The synthetic potential, scope, and limitations of this reaction were illustrated by more than 70 examples. The proposed reaction mechanism invokes the formation of highly reactive CF3-propargyl cation intermediates that can be trapped at the two mesomeric positions by the intermolecular nucleophilic attack of an arene partner with a subsequent intramolecular ring closure. [ABSTRACT FROM AUTHOR]