Fluoroazoles. II. Synthesis and 1H and 19F Nmr spectra of 2-, 4-, and 5-Fluoro-1-methylimidazole

The three possible ring-monofluorinated N-methylimidazoles have been prepared by photochemical irradiation of the corresponding diazonium tetrafluoroborates. 5-Fluoro-1-methyl-imidazole was also obtained by methylation of 1-acetyl-4-fluoroimidazole. The ¹H and ¹⁹F nmr spectra of these N-methylated fluoroazoles are compared, and the predominance of one tautomeric form in 4(5)-fluoroimidazole is discussed.     

15N-, 1H-, and 13C-NMR chemical shifts and electronic properties of aromatic diamines and dianhydrides

We measured the ¹⁵N-, ¹H-, and ¹³C-NMR chemical shifts for a series of aromatic diamines and aromatic tetracarboxylic dianhydrides dissolved in DMSO-d₆, and discuss the relationships between these chemical shifts and the rate constants of acylation (k) as well as such electronic-property-related parameters such as ionization potential (IP), electronic affinity (EA), and the energy ε of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The ¹⁵N chemical shifts of the amino group of diamines (δ_N) depend monotonically on the logarithm of k (log k) and on IP. We inferred the reactivities of diamines whose acylation rates have not been measured from their δ_N, and we propose an arrangement of diamines in the order of their reactivity. The ¹H chemical shift of amino hydrogens (δ_H) and the ¹³C chemical shift of carbons bonded to nitrogen (δ_C) are roughly proportional to δ_N, but these shifts are not as closely correlated with log k and IP. Although the ¹³C chemical shifts of the carbonyl carbon of dianhydrides (δ_C,) varies much less than the δ_C and δ_N of diamines, δ_C, can be an index of acylation reactivity for dianhydrides because it is closely correlated with ε_LUMO. These facts indicate that the chemical shifts of diamines and dianhydrides are displaced according to their electron-donor and electron-acceptor properties, and that these chemical shifts can be used as indices of the electronic properties of monomers. Changes in reactivity caused by the introduction of trifluoromethyl groups into diamines and dianhydrides are inferred from the displacements of δ_N and δ_C © 1992 John Wiley & Sons, Inc.     

Synthesis of 8,9-dihydrodipyrazolo[3,4-b:4′,3′-f][1,5]diazocin-10(1H)-one. A new ring system

8,9-Dihydrodipyrazolo[3,4-b:4′,3′-f][1,5]diazocin-10(1H)-ones 7 were prepared by cyclization of 1-ethyl-N,3-dimethyl-4-acetamido-N-(1-R₁-3-R₂-1H-pyrazol-5-yl)-1H-pyrazole-5-carboxamides 6 by a Bischler-Napieralski cyclization. A complete assignment of the chemical shifts to the carbon atoms of compound 7 was performed by different nmr experiments, such as DEPT and XHDEPT for one? bond C? H correlations and COLOC experiments for long-range C-H correlations.     

Carbon-13 nuclear magnetic resonance spectra of N-substituted 2-amino-4H-3,1-benzoxazin-4-ones and 3-substituted 2,4-(1H,3H)quinazolinediones

¹³C chemical shifts of nine N-substituted 2-amino-4H-3,1-benzoxazin-4-ones, the isomeric 3-substituted 2,4-(1H,3H)quinazolinediones, and the parent compounds of the two series are reported. Support is provided for the endocyclic position of the C=N bond in the former series of compounds.     

Preparation,X-ray crystal structure and 13C- and 1H-NMR study of 1-methyl-2-(N-methyl-N-phenylglycyl)-3-(N-methylanilino)indole

Reaction of N-methylaniline with 40% glyoxal yields 1-methyl-2-(N-methyl-N-phenylglycyl)-3-(N-methylanilino)indole ( 1a ) as the main product together with 1-methyl-3-(N-methylanilino)indole ( 1b ). The reaction appears to be general for aromatic secondary amines since N-ethylaniline and N-phenylbenzylamine yield the corresponding indoles. The structure of 1a has been verified by single crystal X-ray diffraction. Compound 1a (C₂₅H₂₅N₃O) crystallized in the triclinic space group Pl? with cell dimensions a = 10.085(3)Å, b = 10.371(3)Å, c = 11.908(5)Å, α = 74.2(3)°, β = 74.7(3)° and γ = 60.7(2)° with Z = 2. The complete ¹H and ¹³C nmr assignment of indoles 1a and 1b was achieved from two-dimensional HETCOR and COSY spectra with the aid of homonuclear and heteronuclear double resonance experiments.     

The Effect of Electron-Donating and Electron-Withdrawing Substituents on 1H-and 13C-NMR chemical shifts of novel 7′-aryl-substituted 7′-apo-β-carotenes

The synthesis of 7′-aryl-7′-apo-β-carotenes, where aryl (Ar) is Ph, 4-NO₂C₆H₄, 4-MeOC₆H₄, 4-(MeO₂C)C₆H₄, C₆F₅, and 2,4,6-Me₃C₆H₂, is described. NMR Chemical shifts of all H- and C-atoms are presented, together with specific examples of the spectra. In contrast to ¹H chemical shifts which, except for H? C(8′) and H? C(7′), did not differ greatly from those of β,β-carotene, considerable variations in ¹³C chemical shifts were observed. Signals of the C(α) atoms of the polyene chain [C(β)? C(α)] +_n Ar were shielded, those of the C(β) atoms were deshielded, with some exceptions when n = 1; the effects decreased with increasing n.     

Self-assembly of 1-D, 2-D,and 3-D transition-metal coordination polymers based on a T-shaped tripodal ligand 4-(4,5-dicarboxy-1H-imidazol-2-yl)pyridine 1-oxide

Three coordination polymers, {[Co(C₁₀H₅N₃O₅)(H₂O)₂]·H₂O}_n (1), {[Mn₃(C₁₀H₅N₃O₅)₂Cl₂(H₂O)₆]·2H₂O}_n (2), and {[Cu₃(C₁₀H₄N₃O₅)₂(H₂O)₃]·4H₂O}_n (3), based on a T-shaped tripodal ligand 4-(4,5-dicarboxy-1H-imidazol-2-yl)pyridine 1-oxide (H₃DCImPyO), were synthesized under hydrothermal conditions. The polymers showed diverse coordination modes, being characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray structure analysis. In 1, the HDCImPyO^2? generated a 1-D chain by adopting a μ₂-kN, O : kN′, O′ coordination mode to bridge two Co(II) ions in two bis-N,O-chelating modes. In 2, the HDCImPyO^2? adopted a μ₃-kN, O : kO′, O′′ : O′′′ coordination mode to bridge two crystallographically independent Mn(II) ions, forming a 2-D hcb network with {6³} topology. In 3, by adopting μ₄-kN, O : kO′, O′′ : kN′′, O′′′ : O′′′′ coordination, DCImPyO^3? bridged three crystallographically independent Cu(II) ions to form a 3-D framework having the stb topology.     

Synthesis of 2-substituted 1-tosyl-3-(1-tosyliminoalkyl)imidazolidines and-hexahydropyrimidines

Reactions of N-tosylimidoyl chlorides with the Schiff bases of the general formula TsNH(CH₂)_nN=CHR (n = 2 or 3; R = Prⁱ, 4-MeOC₆H₄, 4-Me₂NC₆H₄, and 3-O₂NC₆H₄) afforded 2-substituted 1-tosyl-3-(1-tosyliminoalkyl)imidazolidines (n = 2) or-hexahydropyrimidines (n = 3). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 872–875, May, 2006.     

1H, 13C, 15N and 195Pt NMR studies of Au(III) and Pt(II) chloride organometallics with 2‐phenylpyridine

¹H, ¹³C, ¹⁵N and ¹⁹⁵Pt NMR studies of gold(III) and platinum(II) chloride organometallics with N(1),C(2′)‐chelated, deprotonated 2‐phenylpyridine (2ppy*) of the formulae [Au(2ppy*)Cl₂], trans(N,N)‐[Pt(2ppy*)(2ppy)Cl] and trans(S,N)‐[Pt(2ppy*)(DMSO‐d₆)Cl] (formed in situ upon dissolving [Pt(2ppy*)(µ‐Cl)]₂ in DMSO‐d₆) were performed. All signals were unambiguously assigned by HMBC/HSQC methods and the respective ¹H, ¹³C and ¹⁵N coordination shifts (i.e. differences between chemical shifts of the same atom in the complex and ligand molecules: Δ^1H_coord = δ^1H_complex ? δ^1H_ligand, Δ^13C_coord = δ^13C_complex ? δ^13C_ligand, Δ^15N_coord = δ^15N_complex ? δ^15N_ligand), as well as ¹⁹⁵Pt chemical shifts and ¹H‐¹⁹⁵Pt coupling constants discussed in relation to the known molecular structures. Characteristic deshielding of nitrogen‐adjacent H(6) protons and metallated C(2′) atoms as well as significant shielding of coordinated N(1) nitrogens is discussed in respect to a large set of literature NMR data available for related cyclometallated compounds. Copyright © 2009 John Wiley & Sons, Ltd.     

Crystallographic characterization of three cathinone hydrochlorides new on the NPS market: 1-(4-methylphenyl)-2-(pyrrolidin-1-yl)hexan-1-one (4-MPHP), 4-methyl-1-phenyl-2-(pyrrolidin-1-yl)pentan-1-one (α-PiHP) and 2-(methylamino)-1-(4-methylphenyl)pentan-1-one (4-MPD)

Cathinones belong to a group of compounds of great interest in the new psychoactive substances (NPS) market. Constant changes to the chemical structure made by the producers of these compounds require a quick reaction from analytical laboratories in ascertaining their characteristics. In this article, three cathinone derivatives were characterized by X-ray crystallography. The investigated compounds were confirmed as: 1-[1-(4-methylphenyl)-1-oxohexan-2-yl]pyrrolidin-1-ium chloride ( 1 , C₁₇H₂₆NO⁺·Cl^?, the hydrochloride of 4-MPHP), 1-(4-methyl-1-oxo-1-phenylpentan-2-yl)pyrrolidin-1-ium chloride ( 2 ; C₁₆H₂₄NO⁺·Cl^?, the hydrochloride of α-PiHP) and methyl[1-(4-methylphenyl)-1-oxopentan-2-yl]azanium chloride ( 3 ; C₁₃H₂₀NO⁺·Cl^?, the hydrochloride of 4-MPD). All the salts crystallize in a monoclinic space group: 1 and 2 in P2₁/c, and 3 in P2₁/n. To the best of our knowledge, this study provides the first detailed and comprehensive crystallographic data on salts 1 – 3 .     

Amidrazones. VII. Formation of s-triazines by thermolysis of N1-benzyl-substituted amidrazone ylides

The preparation of ylides of the general structure is described. Thermolysis of 14a (R = CH₃, R' = H, Ar = C₆H₅) gave dimethylamine and 2,4-dimethyl-6-phenyl-s-triazine. Thermolysis of ylides 14b (R = C₆H₅; R' = CH₃, Ar = C₆H₅) and 14c (R = C₆H₅, R' = CH₃, Ar = p-tolyl) gave dimethylamine, ArCH = NCH₃ and 1-methyl-2-Ar-4,6-diphenyl-1,2-dihydro-s-triazines ( 19a,b ). Triazines 19a and 19b were also prepared by condensation of N-methylbenzamidine with benzaldehyde and p-tolualdehyde, respectively. Thermolysis of 14d (R = C₆H₅, R¹ = CH₂C₆H₅,Ar = C₆H₅) gave 1-benzyl-2,4,6-triphenyl-1,2-dihydro-s-triazine ( 19c ) and N-benzylidenebenzylamine. Mechanistic aspects of these reactions are discussed.     

Carbon-13 nuclear magnetic resonance studies of anthraquinones. Part III—correlation of substituent effects for 2-substituted anthraquinones

The ¹³C chemical shifts of 2-substituted and 2,6-disubstituted anthraquinones have been determined and assigned. The C-1, 2, 3, 4, 13 and C-14 chemical shifts of 2-substituted anthraquinones are correlated with the chemical shifts of monosubstituted benzenes. A three-parameter correlation with Swain and Lupton's ? and ? parameters and Schaefer's Q parameter provides relationships for the prediction of all chemical shifts of 2-substituted anthraquinones from the substituent parameters. Q values for the SCH₃, OCOCH₃, C₂H₅ and C(CH₃)₃ groups are proposed. The two types of correlations are compared for predicting chemical shifts.     

1H-NMR Spectroscopy of Gold Drugs. High-Resolution Studies of β-D-Thioglucosetetraacetate Phosphine Complexes of Au(I)

¹H-NMR data (11.74 Tesla) for the gold(I) complexes [R₃P-Au-(2,3,4, 6-tetra-O-acetyl-1-thio-β-D -glucopyranosido-S)] (R = Et, Cyclohexyl, C₆H₅, p-CH₃OC₆H₄) with sulfur coordination to gold, are reported. The resonances associated with the sugar protons have been assigned although these have similar chemical environments. The coordination chemical shifts, Δδ, for the Au? S? C? H proton are ≈? 0.6 ppm, and support S-coordination to gold.     

1H N.m.r. Chemical shifts and hydrogen exchange rates oftrans-[Co(en)2XY]n+ complexes in liquid ammonia

Summary ¹H n.m.r. spectra of coordinated ethylenediamine HN< hydrogens for 23trans-[Co(en)₂XY]ⁿ⁺ complexes and¹H-²H exchange rates for some selected compounds are reported in the solvent liquid ammonia. Assignments are presented for asymmetric complexes. These are based on the chemical shift order of the symmetric complexes. The assignments are confirmed by independent experimental findings including the effect of specific ion-association and the observed exchange rates. The exchange rates follow the relation k_obsd=k⁰+k¹ [N²H₄ClO₄]^–1, illustrative of general base-catalysis; in this case rate-determining proton abstraction by N²H₃ and N²H ₂ ^– , respectively. Chemical shifts and exchange rates in liquid ammonia follow the published order of the aqueous parameters.     

Carbon-13 NMR spectra of a series of para-substituted N,N-dimethylbenzamides. Comparisons of linear free energy relationships for carbon-13 and nitrogen-15 chemical shifts and rotation barriers

All carbon-13 chemical shifts for 11 para-substituted N,N-dimethylbenzamides in 1 mole % chloroform solution are reported, with assignments based upon double resonance experiments, analogy to chemical shifts of benzamide, and self-consistency between experimental and calculated values using recognized substituent parameters. In contrast to earlier reports, the aryl carbon chemical shift assignments for N,N-dimethylbenzamide are C-2, 127.0; C-3, 128.7; C-4, 129.4, and for p-chloro-N,N-dimethylbenzamide are C-1, 134.6; C-4, 135.5 ppm, relative to internal TMS. Good Hammett correlations (σ_p) are reported for ¹³C chemical shifts of C-1 (σ = 11.9 ppm) and even for the carbonyl group (σ = ?2.3 ppm) but are markedly improved if correlated with σ_p+ (σ = 9.5 ppm) and Dewar's F (σ = ?1.9 ppm), respectively. Excellent Swain–Lupton F and R correlations were found for some of the ¹³C chemical shifts and yielded values for percent resonance contributions to transmission of substituent effects as follows, C-1, 75 ± 4%; C-2, 51 ± 3%; C?O, 31±2%. These are compared to similar values calculated from the C?O of benzoic acids of 34±10%, and from the nitrogen-15 chemical shifts of benzamides of 56±2%. Correlations of these ¹³C δ values and ¹⁵N δ values with rotation barriers (ΔG) for N,N-dimethylbenzamides were examined, and it was found that while C?O δ values correlated only poorly the C-1 δ values correlated very well, but the best correlation was for ¹⁵N δ values of benzamides. It is suggested that Δ G and δ ¹⁵N are intrinsically related due to their numerical correlation, and the close similarity in percent resonance contribution of substituent influence on these parameters.     

Synthesis,crystal structures,photoluminescence, electrochemistry and DFT study of aluminium(III) and gallium(III) complexes containing a novel tetradentate Schiff base ligand

Single crystals of the aluminium and gallium complexes of 6,6′‐{(1E,1′E)‐[1,2‐phenylenebis(azanylylidene)]bis(methanylylidene)}bis(2‐methoxyphenol), namely diaqua(6,6′‐{(1E,1′E)‐[1,2‐phenylenebis(azanylylidene)]bis(methanylylidene)}bis(2‐methoxyphenolato)‐κ⁴O¹,N,N′,O^1′)aluminium(III) nitrate ethanol monosolvate, [Al(C₂₂H₁₈N₂O₄)(H₂O)₂]NO₃·C₂H₅OH, 1 , and diaqua(6,6′‐{(1E,1′E)‐[1,2‐phenylenebis(azanylylidene)]bis(methanylylidene)}bis(2‐methoxyphenolato)‐κ⁴O¹,N,N′,O^1′)gallium(III) nitrate ethanol monosolvate, [Ga(C₂₂H₁₈N₂O₄)(H₂O)₂]NO₃·C₂H₅OH, 2 , were obtained after successful synthesis in ethanol. Both complexes crystallized in the triclinic space group P, with two molecules in the asymmetric unit. In both structures, in one of the independent molecules the tetradentate ligand is almost planar while in the other independent molecule the ligand shows significant distortions from planarity, as illustrated by the largest distance from the plane constructed through the central metal atom and the O,N,N′,O′‐coordinating atoms of the ligand in 1 of 1.155 (3) Å and a distance of 1.1707 (3) Å in 2 . The possible reason for this is that there are various strong π‐interactions in the structures. This was confirmed by density functional theory (DFT) calculations, as were the other crystallographic data. DFT was also used to predict the outcome of cyclic voltammetry experiments. Ligand oxidation is more stabilized in the gallium complex. Solid‐state photoluminescence gave an 80 nm red‐shifted spectrum for the gallium complex, whereas the aluminium complex maintains the ligand curve with a smaller red shift of 40 nm.     

Reduktion von 1,2-bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzol: Synthese von Cyclotrisazobenzol ( = (5E,6aZ,11E,12aZ,17E,18aZ)-5,6,11,12,17,18-Hexaazatribenzo[aei][1,3,5,7,9,11]cyclododeca-hexaen)

Reduction of 1,2-Bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzene¹: Synthesis of Cyclotrisazobenzene ( = (5E,6aZ,11E,12aZ,17E,18aZ)-5,6,11,12,17,18-Hexaazatribenzo[aei][1,3,5,7,9,11]cyclododeca-hexaene) Na₂S reduction of 1,2-bis[(Z)-(2-nitrophenyl)-NNO-azoxy]benzene ( 2 ) yielded 3 deoxygenated products: the (known) red 2,2′-((E,E)-1,2-phenylenbisazo)dianiline ( 3 , 23%), the orange 2-[2-((E)-2-aminophenylazo)phenyl]-2H-benzotriazol ( 4 , 55%) and the colorless 2,2′-(1,2-phenylene)di-2H-benzotriazol ( 5 , 13%). The constitutions of 3 – 5 and of 6 , the N-acetyl derivative of 4 , were deduced from their ¹H-NMR spectra (chemical shifts, couplings, and symmetry properties), and the configurations of 3 , 4 , and 6 at their N,N-double bonds are assumed to be the same as in 2 . Oxidation of 3 with 2 mol-equiv. of Pb(OAc)₄ afforded 5 (47%) and a novel, highly symmetrical macrocycle, called cyclotrisazobenzene ( 7 , 24%). The constitution of 7 as a tribenzo-hexaaza[12]annulene and its (E)-configuration at the N,N-bonds was confirmed by X-ray analysis. The molecular symmetry expressed by the ¹H-, ¹³C- and ¹⁵N-NMR spectra of 7 reveals a rapid torsional motion around the six N,C bonds. This implies that the N,N-double bonds in the cyclic 12π-electron system (or 24π-electron system if the benzene rings are included) of 7 are highly localized.     

Tetrazole compounds. 11. electron impact mass spectrometry of 1-aryl-5-(l-acyl-2-dialkylaminovinyl)-1H-tetrazoles

The mass spectrometric behaviour of 1-aryl-5-(1-acyl-2-dialkylaminovinyl)-1H-tetrazoles was studied, especially using 1-phenyl-5-(1-benzoyl-2-dimethylaminovinyl)-1H-tetrazole 1 and its D-and ¹⁵N-labeled derivatives. All tetrazoles investigated showed a clearly observable molecular ion and underwent as the main fragmentation the elimination of nitrogen followed by a number of various subsequent processes. Besides, primary fragments such as [M ? N₃^?]⁺ and [M — ArN₃]^+? were also observed.     

Tryptophan-derived peptides. 1: Crystal structure and solution conformation of Boc-Gly-Trp-Ala-OtBu

The solid-state structure of Boc-Gly-Trp-Ala-OBu^t was determined by single-crystal X-ray diffraction analysis. The tripeptide gave crystals belonging to the orthorhombic systemP2₁2₁2₁ and at 122.0(5) K:a=11.0663(12),b=14.107(2),c=17.275(2) Å,V=2697.0(5) ųZ=4,R(F)=0.0259, andR _w(F)=0.0695. The peptide adopts a type-I-turn in the solid state with a single, rather weak, intramolecular hydrogen bond between the Boc-CO and Ala-NH groups (NO 3.082(1) Å, <NHO 167(1)°). The conformation of the Boc-Gly-Trp-Ala-OBu^t peptide has also been studied by¹H NMR spectroscopy. The solvent and temperature dependencies of NH chemical shifts suggests that this hydrogen bond is broken and that all amide protons are solvent exposed in CDCl₃ and (CD₃)₂SO.     

Intramolecular interactions in nitroamines studied by 1H, 13C, 15N and 17O NMR spectral and quantum chemical methods

¹H, ¹³C, ¹⁵N and ¹⁷O NMR chemical shifts are used for the characterization of the intramolecular interactions in several nitramines of the Me₂N-G-NO₂ type. The charge of lone electron pair of the amino group in N,N-dimethylnitramine, N,N-dimethyl-2-nitroethenamine, N,N-dimethyl-p-nitroaniline, 4-nitro-β-dimethylaminostyrene, 4-N,N-dimethylamino-β-nitrostyrene, 4-(N,N-dimethylamino)-4′-nitrobiphenyl, and 4-(N,N-dimethylamino)-4′-nitrostilbene is transferred not only to the nitro oxygens, but also to the vinylene and benzene carbons of the G spacer and to N-methyl carbons as well. Decreased nuclear shielding is found to be qualitatively related to the decreased atomic charge around a nucleus. This finding was further verified and quantified by comparison of the NMR data with those obtained by ab initio quantum chemical calculations. ¹⁷O NMR chemical shift changes seem to be more significant when the interacting NMe₂ and NO₂ groups are separated by a short spacer. On the other hand, ¹⁵N NMR chemical shifts suggest that a decrease of the charge at the amino nitrogen is not related to the length of the spacer alone. A lack of the linear dependence between the ¹⁷O_nitro and ¹⁵N_amino chemical shifts suggests that the charge lost by the amino nitrogen was only partially gained by the oxygens in the nitro group. The increased shieldings of the aryl carbons in 4-(N,N-dimethylamino)-4′-nitrobiphenyl indicate that atoms of the p,p-biphenylene spacer also gain some charge originating from the amino nitrogen. ³ J _H,H spin–spin coupling constant shows that among different vinylene compounds, the charge transfer to the nitro group is practically effective only in N,N-dimethyl-2-nitroethenamine where the bond between the vinylene carbons is significantly of low order by character. The calculated Natural Population Analysis (NPA) data confirms that except the nitro oxygens, other atoms that receive the negative charge lost by NMe₂ in the compounds studied are the aryl and N-methyl carbons.