The mutual influence between <Emphasis Type="Italic">π</Emphasis>-hole pnicogen bonds and <Emphasis Type="Italic">σ</Emphasis>-hole halogen bonds in complexes of PO<Subscript>2</Subscript>Cl and XCN/C<Subscript>6</Subscript>H<Subscript>6</Subscript> (X = F,Cl, Br)

The bimolecular and termolecular complexes involving PO₂Cl and XCN/C₆H₆ (X = F, Cl, Br) were designed to form the π-hole pnicogen bonds and σ-hole halogen bonds, to compare the two types of interactions and investigate the mutual influences between them. PO₂Cl was used as simultaneous π-hole and σ-hole donor; it can interact with electron donor to form π-hole pnicogen bond and σ-hole halogen bond. The π-hole interactions are stronger than the σ-hole interactions, in both the bimolecular and the termolecular complexes. Comparing the mutual effects of the π-hole interactions and σ-hole interactions, the π-hole interaction has a greater influence on the σ-hole interaction than vice versa. With the addition of σ-hole halogen bond, the V _S,max value outside the π-hole region of PO₂Cl becomes decreasingly positive, resulting in a weaker π-hole interaction. With the addition of π-hole pnicogen bond, the V _S,max value outside the σ-hole region of PO₂Cl becomes small, also resulting in a weaker σ-hole interaction. The π-hole pnicogen bond and σ-hole halogen bond weaken each other, i.e., there is a negative cooperative effect in the termolecular complexes.     

Structural characterization of the crystalline diastereomeric complexes of enantiopure dimethylacridino-18-crown-6 ether and the enantiomers of 1-(1-naphthyl)ethylamine hydrogen perchlorate

This paper describes the X-ray crystal structure of the diastereomeric complexes formed by enantiopure dimethyl-substituted acridino-18-crown-6 ether (R,R)-1 and the enantiomers of 1-(1-naphthyl)ethylammonium perchlorate. We found that the heterochiral complex (R,R)-1–(S)-1-NEA is more stable than the homochiral one (R,R)-1–(R)-1-NEA. In the case of the heterochiral complex, the X-ray studies revealed a strong intermolecular π–π interaction between the naphthyl unit and the acridine moiety. However, in the case of the homochiral complex, π–π interaction was not found. We suggest that the existence or absence of the π–π interaction and the difference in steric repulsions in the diastereomers is responsible for the enantiomeric discrimination.     

Sorption of adamantane phenylamide derivatives on hyper-cross-linked polystyrene from water–acetonitrile eluents

Study of the main physicochemical features of the sorption of phenylamide adamantane derivatives on hyper-cross-linked polystyrene from water–acetonitrile solutions shows that both hydrophobic and electronic interactions make a large contribution to retention, especially for a chlorine-containing derivative in which there are π–p and π–d interactions between the outer-shell electrons of the chlorine atom in addition to π–π interactions between aromatic fragments of the sorbate and sorbent.     

Synthesis of new heterocycles by oxidation of functionalized cyclic derivatives of bis(2-chlorovinyl) sulfide and selenide

Oxidation of 4-substituted 2,6-bis[(E)-chloromethylidene]thiomorpholine with hydrogen peroxide in a mixture of chloroform with acetic acid afforded the corresponding 4-R-2,6-bis[(E)-chloromethylidene]-thiomorpholine 1-oxide. The results of oxidation of bis[(E)-chloromethylidene]-1,4-dichalcogenanes under analogous conditions depended on the chalcogen nature and its position in the ring. The reaction of 2,6-bis[(E)-chloromethylidene]-1,4-dithiane gave 2,6-bis[(E)-chloromethylidene]-1,4-dithiane-1,1,4,4-tetraone, whereas 3,5-bis[(E)-chloromethylidene]-1,4-thiaselenane-1,1-dione was unexpectedly obtained from 3,5-bis[(E)-chloromethylidene]-1,4-thiaselenane. 2,6-Bis[(E)-chloromethylidene]-1,4-thiaselenane and 2,6-bis[(E)-chloromethylidene]-1,4-diselenane decomposed under the oxidation conditions.     

Synthesis of isotactic polystyrene-block-polyethylene by the combination of sequential monomer addition and hydrogenation of 1,4-<Emphasis Type="Italic">trans</Emphasis>-polybutadiene block

Herein, we demonstrate the synthesis of a well-defined diblock copolymer consisting of isotactic polystyrene (iPS) and linear polyethylene, isotactic polystyrene-block-polyethylene (iPS-b-PE), by the combination of sequential monomer addition and hydrogenation. Isospecific living polymerization of styrene and living trans-1,4-polymerization of 1,3-butadiene were catalyzed by 1,4-dithiabutandiyl-2,2′-bis(6-cumenyl-4-methylphenoxy) titanium dichloride (complex 1) activated by triisobutyl aluminum modified methylaluminoxane (MMAO) at room temperature to provide highly isotactic polystyrene (iPS) and 1,4-trans-polybutadiene (1,4-trans-PBD) with narrow molecular weight distribution. Furthermore, the iPS-b-1,4-trans-PBD was synthesized via sequential monomer addition in the presence of complex 1 and MMAO. The hydrogenation of the 1,4-trans-PBD block was promoted by RuCl₂(PPh₃)₃ used as a catalyst to produce iPS-b-PE.     

Chemistry of Acyl(imidoyl)ketenes: IX. Synthesis and Thermolysis of 3-Aroyl-8-chloro-1,2-dihydro-4<Emphasis Type="Italic">H</Emphasis>-pyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazine-1,2,4-triones

Reactions of 3-Z-aroylmethylene-6-chloro-3,4-dihydro-2H-1,4-benzoxazine-2-ones with oxalyl chloride afford 3-aroyl-8-chloro-1,2-dihydro-4H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones and Z-3-(2-aryl-2-chlorovinyl)-6-chloro-2H-1,4-benzoxazine-2-ones. Aroyl(imidoyl)ketenes generated by decarbonylation of pyrrolobenzoxazinetriones undergo dimerization through [4+2]-cycloaddition to form 4-aroyl-3-aroyloxy-2-(2-oxo-2H-1,4-benzoxazin-3-yl)-1H, 5H-pyrido[2,1-c][1,4]benzoxazine-1,5-diones.     

Synthesis of pyranopyrazoles,benzopyrans, amino-2-chromenes and dihydropyrano[<Emphasis Type="Italic">c</Emphasis>]chromenes using ionic liquid with dual Brønsted acidic and Lewis basic sites

An efficient ionic liquid with both Brønsted acidic and Lewis basic sites, namely 1,4-dimethyl-1-(4-sulphobutyl)piperazinium hydrogen sulphate (IL1), was synthesised and characterised. IL1 is a “green”, homogeneous and reusable catalyst for: i) the synthesis of pyranopyrazoles (Va-Vj)and benzopyrans (VIa-VIj and VIIa-VIIf) at ambient temperature under solvent-free conditions and ii) the synthesis of amino-2-chromenes (VIIIa-VIIIi and IXa-IXi) and dihyropyrano[c]chromenes (Xa-Xi) at 80 °C under solvent-free conditions. The reactions were rapid with excellent product yields. In addition, the double Brønsted acid, 1,4-dimethyl-1,4-bis(4-sulphobutyl)piperazinium hydrogen sulphate (IL2), was prepared to evaluate the cooperation efficiency of their Brønsted acidic and Lewis basic sites as compared with the double Brønsted acidic sites in IL1.     

Oxidative trifluoroacetamidation of (1<Emphasis Type="Italic">E</Emphasis>,3<Emphasis Type="Italic">E</Emphasis>)-1,4-diphenylbuta-1,3-diene and 1,1,4,4-tetraphenylbuta-1,3-diene

Reactions of trifluoroacetamide with (1E,3E)-1,4-diphenylbuta-1,3-diene and 1,1,4,4-tetraphenylbuta-1,3-diene in the oxidative system t-BuOCl–NaI have been studied. The reaction with (1E,3E)-1,4-diphenylbuta-1,3-diene afforded three products, N,N′-(phenylmethylene)bis(trifluoroacetamide), 3-chloro-4-iodo- 2,5-diphenyl-1-(trifluoroacetyl)pyrrolidine, and trifluoro-N-[(3E)-2-hydroxy-1,4-diphenylbut-3-en-1-yl]acetamide, with a high overall yield. 1,1,4,4-Tetraphenylbuta-1,3-diene failed to react with trifluoroacetamide.     

Binuclear copper(II) complexes with acyldihydrazones of 1,4-cyclohexanedicarboxylic acid

The binuclear copper(II) complexes with acyldihydrazones formed by 1,4-cyclohexanedicarboxylic acid and salicylaldehyde or 2-hydroxyacetophenone were synthesized and studied. The structure of the complex with 1,4-cyclohexanedicarboxylic acid bis(salicylidene)hydrazone (H₄L¹) [Cu₂L¹(Py)₂] was studied by X-ray diffraction. The crystals are triclinic: a = 8.1852(4) Å, b = 8.5157(5) Å, c = 11.6553(7) Å, α = 80.678(3)°, β = 70.041(4)°, γ = 74.803(3)°. Space group \(P\bar 1\), Z = 1. The number of symmetrically independent reflections with I > 2(σ(I)) is 2245, R = 0.0395; R _w = 0.0917. The complex contains two equivalent copper atoms located at a 10.772 Å distance from each other. The coordination polyhedra have a square geometry and are involved in the intermolecular π/π-stacking. The EPR spectra of solutions of the binuclear complexes show an isotropic signal of seven HFS lines (g = 2.113–2.118, A _Cu ≈ 38 G), indicating interaction between the unpaired electrons and the two equivalent copper nuclei. The possible exchange interaction channels were analyzed.     

Synthesis,Structure, and Biological Activity of Products of Reactions of 3,4-Dioxohexane-1,6-dioic Acid Esters with 2-Aminophenol

Bioactive derivatives of 1,4-benzoxazine have been prepared via reactions of 3,4-dioxohexane-1,6- dioic (ketipic) acid esters with 2-aminophenol. (2'Z)-2,2'-(2-Hydroxy-2H-1,4-benzoxazin-2-yl-3-ilidene)diacetic acid esters or (2Z)-[2-oxo-2H-1,4-benzoxazin-3(4H)-ylidene]acetic acid esters can be formed depending on the conditions. The structures of the products of dialkyl ketipate esters reactions with 2-aminophenol were determined by means of X-ray diffraction. It has been demonstrated that the prepared compounds exhibit antimycotic activity against test cultures of plant pathogenic fungi (Fusauium sp., Alternarium sp., and Bipolaris soraciniana).     

<Emphasis Type="Italic">S</Emphasis>-functional derivatives of 3,4-dihydro-2<Emphasis Type="Italic">H</Emphasis>-1,4-thiasilines

The first cyclic unsaturated S-functional derivatives of 4,4-diphenyl-3,4-dihydro-2H-1,4-thiasiline, S-oxide, S,S-dioxide, and S-sulfonimide, were prepared. Oxidation of the hydrolytically less stable 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline leads to the corresponding sulfoxide and sulfone along with the ring opening products, siloxanes containing the sulfoxide or sulfonyl group.     

Hetero-Diels–Alder reaction of 3-aroylpyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazines with styrene. Synthesis of pyrano[4′,3′: 2,3]pyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazines

The hetero-Diels–Alder reaction of 3-aroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with styrene afforded mixtures of diastereoisomeric (10R*,11aR*)- and (10S*,11aR*)-8-aryl-10-phenyl-10,11-dihydropyrano[4′,3′: 2,3]pyrrolo[2,1-c][1,4]benzoxazine-6,7,12-triones.     

Alternative preparation and characterization of platinum(II) organometallic dinuclear complexes and oligomers with 3,8-diethynylphenanthroline derivatives

Novel platinum(II) organometallic dinuclear complexes and oligomers with two types of phenanthroline ligands, namely 3,8-diethynylphenanthroline (L1) and 3,8-bis-(4-ethynyl-phenylethynyl)-1,10-phenanthroline (L2), were synthesized from trans-Pt(PBu₃)₂(1-ethynyl-4-methyl-benzene)Cl and trans-Pt(PBu₃)₂Cl₂ by transmetalation of copper ion. The alternative procedure targeted platinum oligomer termination selection of either chloride or respective phenanthrolines and was successfully performed with different purifications by extraction and column chromatography. The structural formulae of these platinum complexes and oligomers were revealed with by analysis of both ³¹P{¹H}-NMR and ¹H-NMR spectral data. Alternative preparations of platinum oligomers with two types between chloride and respective phenanthroline termination are very useful for the selective synthesis for hybrid polymers with the coupling reaction with two different platinum oligomers with different diethynylaryl ligands. The platinum organometallic compounds showed similar absorption bands in the UV–Vis region. Those prepared with L1 had a strong absorption band at around 400 nm, assignable to the lowest energy metal-perturbed ¹[π–π*] transitions, while in compounds prepared with L2, the strong band appeared around 410 nm, because L2 has an extended π conjugation relative to L1. No distinct differences were observed in the absorption spectra of these platinum oligomers between the different terminal structures, chloride or various phenanthrolines. The luminescence spectra of the platinum compounds prepared with either L1 or L2, however, showed a distinct difference. Those with L1 showed only a phosphorescence assignable to a typical metal-perturbed ³[π–π*] transition with vibronic progressions centered at around 530 nm in deoxygenated CH₂Cl₂ at room temperature, while those with L2 showed weak dual emissions assignable to a mixture of typical metal-perturbed ¹[π–π*] and ³[π–π*] transitions in the visible region.     

Monofluoro-substituted azomethine ylides in fluorocarbene reactions with imines. Synthesis and transformations of monofluoroaziridines

N-Arylmethylene and N-benzhydrylideneamines react with fluorocarbene yielding fluoro-substituted azomethine ylides that undergo 1,3-π-cyclization into aziridines. Generation of fluoroylides in the presence of dipolarophiles (dimethyl maleate or dimethyl acetylenedicarboxylate) led to the reaction of 1,3-dipolar cycloaddition resulting in substituted 2-pyrrolines or pyrroles. 2-Fluoroaziridines, products of N-alkyl-N-benzhydrylideneamines 1,3-π-cyclization, in the presence of acid catalysts suffer isomerization into α-fluoroimines and 1,3-disubstituted indoles.     

Reaction of N-substituted 2,5-dialkyl-1,4-benzoquinone imines with arenesulfinic acids

Reactions of N-aroyl-, N-arylsulfonyl-, and N-(N-arylsulfonylbenzimidoyl)-2,5-dialkyl-1,4-benzoquinone imines with sodium arenesulfinates in acetic acid gave the corresponding 1,4-, 6,1-, and 1,6-addition products. Variation of the size and donor power of substituents in positions 2 and 5 of the quinoid ring almost does not affect the ratio of the addition products, which is determined mainly by the nature of substituent on the nitrogen atom.     

Solvothermal synthesis and crystal structure of a 1d coordination polymer: [Ni(1,4-BDC)(N-MIM)<Subscript>2</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> (1,4-BDC = 1,4-benzenedicarboxylic acid,N-MIM = <Emphasis Type="Italic">N</Emphasis>-methylimidazole)

A new metal-organic coordination polymer, namely [Ni(1,4-BDC)(N-MIM)₂] _n (I) (1,4-BDC = 1,4-benzenedicarboxylic acid and N-MIM = N-methylimidazole), has been synthesized under solvothermal conditions by using N-MIM as solvent and characterized by elemental analysis, IR, and X-ray single-crystal diffraction. The X-ray diffraction analysis reveals that I crystallizes in the monoclinic system, space group C2/c. The 1,4-BDC ligand adopts a bis(bidentate) chelating mode to connect two adjacent Ni(II) centers to form a one-dimensional (1D) zigzag chain. The adjacent chains are further linked through hydrogen bonds and π-π stacking interactions, forming a three-dimensional (3D) supramolecular framework. The unit cell parameters for I: a = 17.250(10), b = 7.214(4), c = 16.506(7)Å, β = 125.53(4)°, V = 1671.6(15)ų, Z = 4.     

Synthesis of 13-alkylbenzo[<Emphasis Type="Italic">f</Emphasis>]isochromeno[4,3-<Emphasis Type="Italic">b</Emphasis>]indole-5,7,12(13<Emphasis Type="Italic">H</Emphasis>)-triones by reaction of 2-alkylamino-1,4-naphthoquinones with ninhydrin

Reactions of 2-alkylamino-1,4-naphthoquinones with 2,2-dihydroxy-1H-indene-1,3(2H)-dione afforded 13-alkylbenzo[f]isochromeno[4,3-b]indole-5,7,12(13H)-triones.     

Synthesis of ditopic ligands containing bis(1<Emphasis Type="Italic">H</Emphasis>-pyrazol-1-yl)-methane fragments

New approaches have been proposed for the synthesis of compounds containing two bis(1H-pyrazol-1-yl)methane fragments. Nucleophilic replacement of the halogen atoms in appropriate tetrabromo derivatives by pyrazoles in the superbasic system KOH-DMSO gave ditopic chelating ligands: 1,1,2,2-tetrakis(1H-pyrazol-1-yl)ethane, 1,4-bis[bis(1H-pyrazol-1-yl)methyl]benzene, and 1,4-bis[bis(3,5-dimethyl-1H-pyrazol-1-yl)methyl]benzene. 1,4-Bis[bis(1H-pyrazol-1-yl)methyl]benzene was also synthesized by reaction of 1H-pyrazole with terephthalaldehyde in the presence of thionyl chloride. 1,1,2,2-Tetrakis(1H-pyrazol-1-yl)ethane was converted into the corresponding tetraiodo and tetranitro derivatives.     

Synthesis and antimicrobial evaluation of 2-hydroxynaphthalene-1,4-dione and 4<Emphasis Type="Italic">H</Emphasis>-chromene conjugates

4H-Chromene and 1,4-naphthoquinone systems are generally considered to be medicinally privileged scaffolds. We have designed novel conjugates that incorporated both these scaffolds, as such conjugates exhibit unique biological properties reflecting those due to individual units and collective presence. In this work, we have achieved facile, efficient, and high yielding synthesis of 19 such conjugates from readily available 2-alkylamino-4-methylsulfanyl-3-nitro-4H-chromenes and 2-hydroxynaphthalene-1,4-dione. Highly polar nitroketene-O,N-acetal unit present in the conjugates is designed to prevent crossing blood brain barrier. We have conducted structure activity relationship (SAR) studies based on initial antimicrobial screening of a set of ten conjugates against three Gram positive bacteria [Bacillus Subtilis, Staphylococcus aureus (MSSA), Staphylococcus Escherichia coli), and two fungi (Aspergillus niger, Candida albicans). The SAR studies revealed that the conjugates with halogens at C(6) and C(8) positions of the 4H-chromene ring having C(2)NMe group display impressive activity, almost equal to that of standard drugs. None of the conjugates, however, showed antimalarial activity, although they possess 2-hydroxy-1,4-naphthoquinone unit.     

Thiocyanation of <Emphasis Type="Italic">N</Emphasis>-arylsulfonyl-, <Emphasis Type="Italic">N</Emphasis>-aroyl-, and <Emphasis Type="Italic">N</Emphasis>-[(<Emphasis Type="Italic">N</Emphasis>-arylsulfonyl)benzimidoyl]-1,4-benzoquinone imines

Reactions of thiocyanate ion with N-aroyl-, N-arylsulfonyl-, and N-(N-arylsulfonylbenzimidoyl)-1,4-benzoquinone imines follow the 1,4-addition pattern, and the adducts undergo intramolecular cyclization to give the corresponding N-substituted 5-amino-1,3-benzoxathiol-2-ones as final products.