N—H...O and N—H...N interactions in three pyran derivatives

The three pyran structures 6‐methylamino‐5‐nitro‐2,4‐diphenyl‐4H‐pyran‐3‐carbonitrile, C₁₉H₁₅N₃O₃, (I), 4‐(3‐fluorophenyl)‐6‐methylamino‐5‐nitro‐2‐phenyl‐4H‐pyran‐3‐carbonitrile, C₁₉H₁₄FN₃O₃, (II), and 4‐(4‐chlorophenyl)‐6‐methylamino‐5‐nitro‐2‐phenyl‐4H‐pyran‐3‐carbonitrile, C₁₉H₁₄ClN₃O₃, (III), differ in the nature of the aryl group at the 4‐position. The heterocyclic ring in all three structures adopts a flattened boat conformation. The dihedral angle between the pseudo‐axial phenyl substituent and the flat part of the pyran ring is 89.97 (1)° in (I), 80.11 (1)° in (II) and 87.77 (1)° in (III). In all three crystal structures, a strong intramolecular N—H...O hydrogen bond links the flat conjugated H—N—C=C—N—O fragment into a six‐membered ring. In (II), molecules are linked into dimeric aggregates by N—H... O(nitro) hydrogen bonds, generating an R₂²(12) graph‐set motif. In (III), intermolecular N—H...N and C—H...N hydrogen bonds link the molecules into a linear chain pattern generating C(8) and C(9) graph‐set motifs, respectively.     

Quantum chemical metabolism‐based simulation of carcinogenic potency of benzene derivatives

Using an oxenoid model, we investigated dependences of carcinogenic potency of the benzenes C₆H₅‐X on a nature of substituents X. According to the model, a P450 enzyme breaks a dioxygen molecule and generates the oxens, which readily react with substrates. We suggest that a stability of the intermediate OC₆H₆‐X with tetrahedrally coordinated C atom relative to the molecule C₆H₅‐X determines a rate of substrate biotransformation. Using MO LCAO MNDO approach, we calculated the total energies of molecules C₆H₆‐X and arene oxides OC₆H₆‐X. A difference ΔE_min of these values determines activation energy of oxidation reaction. The compounds with the low ΔE_min values are noncarcinogenic. Benzene derivatives with high ΔE_min values belong to carcinogenic compounds series. The carcinogenicity of amino‐ and nitro‐substituted benzenes is also determined by N‐oxidation of amino and reduction of the nitro group. As the phenylhydroxylamines XC₆H₄NHOH and nitrenium ions XC₆OH₄NH⁺ are the common metabolites of the nitro‐ and amino‐substituted benzenes and nitrenium ions XC₆H₄NH⁺ are the ultimate carcinogens, we use the differences ΔE_N = E(XC₆H₄NH⁺) ? E(XC₆H₄NHOH) as the second parameter characterizing the carcinogenic activity of amino‐ and nitro‐substituted benzenes. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

An efficient in situ reduction and cyclization reaction for synthesis of spiro compound derivatives in Fe–H2O–AcOH medium from nitro compounds

An efficient in situ reduction and cyclization reaction for the synthesis of nitrogen‐containing spiro compounds directly form 5‐nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole in Fe–H₂O–AcOH medium is reported. 5‐Nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole were first used to synthesize spiro compounds, and this is a novel method for the synthesis of spiro compounds from nitro compounds. The advantages of this reaction are stable reagents, easily available raw materials, wide range of substrates and high yields.     

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and its Complexes with Copper(II) Chloride and Copper(II) Perchlorate

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole (hnt), prepared by alkylation of 3‐nitro‐1, 2, 4‐triazole with 2‐chloroethanol, was found to react with copper(II) chloride and copper(II) perchlorate in acetonitrile/ethanol solutions giving complexes [Cu₂(hnt)₂Cl₄(H₂O)₂] and[Cu(hnt)₂(H₂O)₃](ClO₄)₂, respectively. They are the first examples of coordination compounds with a neutral N‐substituted 3‐nitro‐1, 2, 4‐triazole ligand. 1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and the obtained complexes were characterized by NMR and IR spectroscopy, X‐ray, and thermal analyses. [Cu₂(hnt)₂Cl₄(H₂O)₂] presents a dinuclear chlorido‐bridged complex in which hnt acts as a chelating bidentate ligand, coordinated to the metal by a nitrogen atom of the triazole ring and an oxygen atom of the nitro group, and the copper atoms are inconsiderably distorted octahedral coordination. [Cu(hnt)₂(H₂O)₃](ClO₄)₂comprises a mononuclear complex cation, in which two nitrogen atoms of two hnt ligands in trans configuration and three water oxygen atoms form a square pyramidal environment around the copper atom, which is completed to an distorted octahedron with a bifurcated vertex due to two additional elongated Cu–O bonds with two nitro groups. In both complexes, Cu–O bonds with the nitro groups may be considered as semi‐coordinated.     

Triclinic and orthorhombic polymorphs of 2‐iodo‐4‐nitro­aniline: interplay of hydrogen bonds,nitro⃛I interactions and aromatic π–π‐stacking interactions

In the triclinic polymorph of 2‐iodo‐4‐nitro­aniline, C₆H₅IN₂O₂, space group P, the mol­ecules are linked by paired N—­H?O hydrogen bonds into C(8)[R(6)] chains of rings. These chains are linked into sheets by nitro?I interactions, and the sheets are pairwise linked by aromatic π–π‐stacking interactions. In the orthorhombic polymorph, space group Pbca, the mol­ecules are linked by single N—H?O hydrogen bonds into spiral C(8) chains; the chains are linked by nitro?O interactions into sheets, each of which is linked to its two immediate neighbours by aromatic π–π‐stacking inter­actions, so producing a continuous three‐dimensional ­structure.     

Soft C—H⃛O hydrogen bonds in methyl 2,4‐di­nitro­benzene­sulfenate: sheets built from R22(10) and R66(42) rings

Molecules of the title compound, C₇H₆N₂O₅S, are linked into sheets containing R₂²(10) and R₆⁶(42) rings by C—H?O hydrogen bonds [C?O 3.405 (3) and 3.511 (2) Å; C—H?O 159 and 169°], in which both acceptors are in the same nitro group. Comparisons are made with the hydrogen bonding in other nitro­benzene­sulfenate esters.     

1-Acyl-and 1,2-dihydro-1<Emphasis Type="Italic">H</Emphasis>(acyl)deoxyvasicinones. Synthesis and chemical transformations

1-Acyl-and 1,2-dihydro-1H(methyl, acyl)deoxyvasicinones were synthesized. Their PMR and ¹³C NMR spectra were investigated. The chemical shifts and SSCC were determined. 1-Acyl derivatives were produced by acylation of 1,2-dihydrodeoxyvascinone with caprylyl-and chloroacetylchlorides. It was shown that the Cl atom of 1-chloroacetyldeoxyvasicinone was labile and underwent nucleophilic substitution by amines. In contrast with this, it reacted with cyanide, hydroselenide, methoxide, phenoxide, and anions of compounds with an activated methylene group in a completely different direction to cleave the chloroacetyl group and form 1,2-dihydrodeoxyvasicinone. It was found that addition of 1,2-dihydrodeoxyvasicinone to phenylacetylene occurred regio-and stereoselectively to form the cis-isomer of 1-(2-phenylvinyl)-1,2-dihydrodeoxyvasicinone. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 353–359, July–August, 2007.     

Vinylation of Nitro‐Substituted Indoles,Quinolinones, and Anilides with Grignard Reagents

The reaction of vinyl Grignard reagents with o‐methoxynitroarenes containing an electron‐releasing substituent para to the nitro group proceeds through a pathway that is different from the initially expected Bartoli indole synthesis. Thus, instead of giving fused indole derivatives, these reactions provide a very mild and efficient new procedure for the synthesis of synthetically relevant aromatic systems containing an o‐nitrovinyl moiety, such as 5‐nitro‐4‐vinylindoles, 6‐nitro‐7‐vinylindoles, 6‐nitro‐5‐vinyl‐2(1H)quinolinones, and 4‐nitro‐3‐vinylanilines.     

Structural studies and antileishmanial activity of 2‐acetylpyridine and 2‐benzoylpyridine nitroimidazole‐derived hydrazones

Three imidazole hydrazone compounds, namely 2‐(4‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[1‐(pyridin‐2‐yl)ethylidene]acetohydrazide, C₁₂H₁₂N₆O₃, ( 1 ), 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[1‐(pyridin‐2‐yl)ethylidene]acetohydrazide, C₁₂H₁₂N₆O₃, ( 2 ), and 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N′‐[(phenyl)(pyridin‐2‐yl)methylidene]acetohydrazide, C₁₇H₁₄N₆O₃, ( 3 ), were obtained and fully characterized, including their crystal structure determinations. While all the compounds proved not to be cytotoxic to J774.A1 macrophage cells, ( 1 ) and ( 3 ) exhibited activity against Leishmania chagasi, whereas ( 2 ) was revealed to be inactive. Since both ( 1 ) and ( 3 ) exhibited antileishmanial effects, while ( 2 ) was devoid of activity, the presence of the acetyl or benzoyl groups was possibly not a determining factor in the observed antiprotozoal activity. In contrast, since ( 1 ) and ( 3 ) are 4‐nitroimidazole derivatives and ( 2 ) is a 2‐nitroimidazole‐derived compound, the presence of the 4‐nitro group probably favours antileishmanial activity over the 2‐nitro group. The results suggested that further investigations on compounds ( 1 ) and ( 3 ) as bioreducible antileishmanial prodrug candidates are called for.     

One‐Pot Knoevenagel–Michael–Cyclization Cascade Reaction for the Synthesis of Functionalized Novel 4H‐pyrans by Using ZnCl2 as a Catalyst

An expedient and cost‐effective protocol has been developed for the synthesis of novel 2‐methyl‐6‐(methylamino)‐5‐nitro‐4‐(4‐aryl)‐4H‐pyran‐3‐carboxylate derivatives. This domino, one‐pot, three‐component reaction was carried out between β‐ketoesters, aromatic aldehydes, and (E)‐N‐methyl‐1‐(methylthio)‐2‐nitroethenamine (NMSM) in the presence of 30 mol% anhydrous ZnCl₂ under the neat condition at 120°C. The synthesized 4H‐pyran derivatives were characterized by spectroscopic techniques such as IR, ¹H NMR, ¹³C NMR, CHNS, and HRMS. The molecular structure of compound methyl‐2‐methyl‐6‐(methylamino)‐5‐nitro‐4‐(4‐nitrophenyl)‐4H‐pyran‐3‐carboxylate 4a was confirmed by the single crystal X‐ray analysis. This solvent‐free protocol has several advantages such as shorter reaction time, an inexpensive catalyst, good yields, simple workup, and column‐free purification.     

Electrophilic substitution in benzo[b]thieno[2,3-c]pyridines. Nitration

A study was carried out on the nitration of substituted benzo[b]thieno[2,3-c]pyridines. Depending on the conditions, either one nitro group is introduced at C₍₆₎ or two nitro groups are introduced at C₍₆₎ and C₍₈₎. If C₍₆₎ is blocked, a mixture of products is formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 706–709, May, 1993.     

Construction of two Novel 2D Coordination Frameworks with the Ligand H3nbtc: Synthesis,Crystal Structures,and Luminescence

Two novel 2D coordination polymers, namely, {[Cu₂(L)₂][Cu(H₂O)₃]}_n ( 1 ) and {Pb₃(O₂N‐btb)₂}_n ( 2 ) (O₂N‐H₃btb = 5‐nitro‐benzene‐1, 2, 3‐tricarboxylic acid, L = 5‐nitro‐2‐oxidoisophthalate), were synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, X‐ray diffraction, and thermogravimetric analysis. Compound 1 is an infinite 2D layer exhibiting an extended 3D supramolecular network structure. O–H ··· O hydrogen bonding interactions play a key role in forming the final 3D supramolecular framework. It is noted that 5‐nitro‐benzene‐1, 2, 3‐tricarboxylic acid (O₂N‐H₃btb) was in situ transformed to 5‐nitro‐2‐oxidoisophthalate in 1 . Compound 2 is a 2D microporous lead‐containing metal‐organic framework made up of interconnected Pb‐carboxylate chains, involving three independent lead atoms with three different coordination arrangements. Furthermore, the solid‐state photoluminescence and lifetime characteristics of 2 reveal intense blue luminescence.     

Direction of bromination and nitration of deoxypeganine and its hydrochloride using HPTLC. Synthesis of 6-bromo(nitro)-, 6,8-dinitrodeoxyvasicinones, 6-nitro(bromo)-, 6,8-dinitrodeoxypeganines,and 6H(bromo)peganols

The reaction of deoxypeganine (DOP) (1) and its hydrochloride (DOP·HCl) (2) with N-bromosuccinimide and a nitrating mixture was studied. It was found that bromination of DOP occurred at C-4 and the aromatic ring. Nitration of DOP·HCl produced either 6-nitro- or 6,8-dinitro-deoxypeganines and 6-nitrodeoxyvasicinone or their mixture in various ratios depending on the substrate:nitrating mixture ratio. 6Hand 6-Br-deoxypeganines were transformed into the 4-hydroxy derivatives, 6H(Br) peganols or deoxyvasicinones. A method for qualitative and quantitative analysis of the pure compounds and the mixture of reaction products using HPTLC was developed. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 505–509, September-October, 2008. Original article submitted March 26, 2008.     

Hexachloroantimonate(V) mit Nitroderivaten als Liganden, 3. Mitt.: Komplexe Verbindungen mit dreiwertigen Metallen

Complex compounds of trivalent metal chlorides (AlCl₃, CrCl₃, FeCl₃) are described, which had been obtained in a double complexation reaction in CCl₄ as a solvent with nitro compounds and SbCl₅:M ^III(C₆H₅NO₂) _m (SbCl₆)₃ (m=3,6),M ₂ ^III(C₆H₅NO₂)₄(SbCl₆)₄ and Al(-C₁₀H₇NO₂)₃(SbCl₆)₃. Synthesis, analytical results and i.r. spectra are discussed.     

Phototransformations of 6-X-5-Nitroquinoxalines

Photophysical properties and photochemical activity of 6-X-5-nitroquinoxalines with electron-donor substituents (X = H, CH₃, Cl, OC₂H₅, NH₂) ortho to the nitro group were studied. The quantum yield of the formation of 5-hydroxyquinoxaline from the corresponding nitro derivative depends on the nature of the substituent and irradiation conditions. Phototransformations can go through nitro-nitrite rearrangement with the participation of two alternative T(n*) levels, depending on the size and electronic effects of the substituent. The latter factor is largely determined by the population on excitation of different charge-transfer states involving the nitro group.     

6(5H)-phenanthridinones. II. Preparation of substituted 6(5h)-phenanthridinones from 9-oxofluorenes

A number of 6(5H)-phenanthridinones have been conveniently prepared from 9-oxofluorenes through the Schmidt reaction. It has been found that all amino and nitro 9-oxofluorenes thus far tried gave substituted 6(5H)-phenanthridinones with the amino or nitro group situated in the benzene ring attached to the nitrogen of the lactam group. UV and IR spectral data are presented for these compounds.     

Structural and magnetic studies on mono- and polynuclear chromium ascorbate complexes

Polynuclear chromium ascorbate complexes were isolated and physicochemically analyzed in a comparative manner with their mononuclear analog (1). Characterization by elemental analysis, electronic, vibrational, ¹³C-n.m.r and mass spectroscopies, and variable temperature magnetic susceptibility studies, allowed structural proposals for the binuclear, [Cr₂(μ-OH)₂(H₂O)(C₆H₇O₆)₃(OH)] · 4H₂O (2), and trinuclear, [Cr₃(μ-O)₃(H₂O)₆(C₆H₇O₆)₃] · 4 H₂O (3) complexes. The pseudo-octahedral Cr^III centers were suggested to be connected through hydroxo bridges in (2) and in (3) by oxo bridges forming a hexocyclic ring. An erratum to this article is available at .     

Electrochemical Synthesis of MII Complexes with a Schiff Base containing an Amido Group. Crystal Structure of a Cobalt(II) Complex with a Reorganised Ligand

M(HL)(H₂O)_n complexes have been obtained by the electrochemical reaction of Fe, Co, Ni, Cu, Zn and Cd anodes with the potentially pentadentate and trianionic asymmetrical Schiff base 3‐aza‐N‐{2‐[1‐aza‐2‐(5‐nitro‐2‐hydroxylphenyl)‐vinyl]phenyl}‐4‐(5‐nitro‐2‐hydroxyphenyl)but‐3‐enamide (H₃L), containing a hard amido donor atom. The complexes have been characterized by elemental analysis, mass spectrometry, IR and ¹H NMR spectroscopies, magnetic measurements and molar conductivities. Co(HL)(H₂O) ( 2 ) has been found to rearrange in DMF solution into a crystallographically solved octahedral complex, CoL¹(H₂O)₂ ( 7 ) [where H₂L¹ is the symmetrical Schiff base ligand N,N′‐(1,2‐phenylene)‐bis(5‐nitro‐3‐hydroxysalicylidenimine)]. A hydrolysis mechanism is discussed to explain this rearrangement.     

Hydrogen bonding in 4‐nitrobenzene‐1,2‐diamine and two hydrohalide salts

The structures of 4‐nitrobenzene‐1,2‐diamine [C₆H₇N₃O₂, (I)], 2‐amino‐5‐nitroanilinium chloride [C₆H₈N₃O₂⁺·Cl⁻, (II)] and 2‐amino‐5‐nitroanilinium bromide monohydrate [C₆H₈N₃O₂⁺·Br⁻·H₂O, (III)] are reported and their hydrogen‐bonded structures described. The amine group para to the nitro group in (I) adopts an approximately planar geometry, whereas the meta amine group is decidedly pyramidal. In the hydrogen halide salts (II) and (III), the amine group meta to the nitro group is protonated. Compound (I) displays a pleated‐sheet hydrogen‐bonded two‐dimensional structure with R₂²(14) and R₄⁴(20) rings. The sheets are joined by additional hydrogen bonds, resulting in a three‐dimensional extended structure. Hydrohalide salt (II) has two formula units in the asymmetric unit that are related by a pseudo‐inversion center. The dominant hydrogen‐bonding interactions involve the chloride ion and result in R₄²(8) rings linked to form a ladder‐chain structure. The chains are joined by N—H...Cl and N—H...O hydrogen bonds to form sheets parallel to (010). In hydrated hydrohalide salt (III), bromide ions are hydrogen bonded to amine and ammonium groups to form R₄²(8) rings. The water behaves as a double donor/single acceptor and, along with the bromide anions, forms hydrogen bonds involving the nitro, amine, and ammonium groups. The result is sheets parallel to (001) composed of alternating R₅⁵(15) and R₆⁴(24) rings. Ammonium N—H...Br interactions join the sheets to form a three‐dimensional extended structure. Energy‐minimized structures obtained using DFT and MP2 calculations are consistent with the solid‐state structures. Consistent with (II) and (III), calculations show that protonation of the amine group meta to the nitro group results in a structure that is about 1.5 kJ mol⁻¹ more stable than that obtained by protonation of the para‐amine group. DFT calculations on single molecules and hydrogen‐bonded pairs of molecules based on structural results obtained for (I) and for 3‐nitrobenzene‐1,2‐diamine, (IV) [Betz & Gerber (2011). Acta Cryst. E 67 , o1359] were used to estimate the strength of the N—H...O(nitro) interactions for three observed motifs. The hydrogen‐bonding interaction between the pairs of molecules examined was found to correspond to 20–30 kJ mol⁻¹.