Triazene derivatives of (1,x)-diazacycloalkanes — Part IX. Synthesis and characterization of a series of 1,4-di[2-aryl-1-diazenyl]-2,6-dimethylpiperazines

2010 ◽  
Vol 88 (4) ◽  
pp. 344-351 ◽  
Author(s):  
Naomi Hunter ◽  
Keith Vaughan
Keyword(s):  
Diazonium Salt ◽  
Mass Measurement ◽  
2D Nmr ◽  
Piperazine Ring ◽  
Ir And Nmr Spectroscopy ◽  
Methylene Groups ◽  
Type 3 ◽  
Derivatives Of

A series of 1,4-di-[2-aryl-1-diazenyl]-2,6-dimethylpiperazines (5a–5l), have been synthesized by the reaction of 2,6-dimethylpiperazine with 2 equiv. of the appropriate diazonium salt. The products have been characterized by IR and NMR spectroscopy, and the molecular composition has been verified by high-resolution EI mass spectrometry with accurate mass measurement of the molecular ion. The presence of stereocenters at C2 and C6 of the piperazine ring in the bis-triazene 5 creates two unique pairs of diastereotopic protons in the methylene groups at positions 3 and 5 of the piperazine ring, as evidenced by the complexity of the NMR spectra, which nevertheless can be fully assigned in most cases. The assignment of the proton and carbon signals in the 1,4-di-[2-aryl-1-diazenyl]-2,6-dimethylpiperazines has been aided by the use of 2D NMR HSQC spectroscopy. These results compare favorably with assignments of proton and carbon signals reported previously for triazenes of type 1 and bis-triazenes of type 3.

Triazene derivatives of (1,x)-diazacycloalkanes. Part X. Synthesis and characterization of a series of 1,4-di[2-aryl-1-diazenyl]-trans-2,5-dimethylpiperazines

2014 ◽  
Vol 92 (7) ◽  
pp. 665-669 ◽  
Author(s):  
Vanessa Renee Little ◽  
Reid Tingley ◽  
Keith Vaughan
Keyword(s):  
Nmr Spectra ◽  
Diazonium Salt ◽  
Mass Measurement ◽  
2D Nmr ◽  
Piperazine Ring ◽  
Ir And Nmr Spectroscopy ◽  
Methylene Groups ◽  
Derivatives Of

A series of 1,4-di[2-aryl-1-diazenyl]-trans-2,5-dimethylpiperazines(5a–5m), have been synthesized by the reaction of trans-2,5-dimethylpiperazine with two equivalents of the appropriate diazonium salt. The products have been characterized by IR and NMR spectroscopy, and the molecular composition has been verified by high-resolution EI mass spectrometry with accurate mass measurement of the molecular ion. The presence of stereocenters at C2 and C5 of the piperazine ring in the bis-triazene (5) creates two unique pairs of diastereotopic protons in the methylene groups at positions 3 and 6 of the piperazine ring, as evidenced by the complexity of the NMR spectra, which nevertheless can be fully assigned in some cases, such as the anisyl- (5i) and phenyl- (5j) derivatives. The assignment of the proton and carbon signals in the tolyl- derivative (5h) has been aided by the use of 2D NMR HSQC spectroscopy. These results compare favorably with assignments of proton and carbon signals reported previously for triazenes of type 1 and bis-triazenes of types 3 and 4b.

Triazene derivatives of (1,x)-diazacycloalkanes. Part VIII. Synthesis and characterization of a series of 1,4-di[2-aryl-1-diazenyl]-2-methylpiperazines1

2007 ◽  
Vol 85 (3) ◽  
pp. 189-196 ◽  
Author(s):  
Naomi Hunter ◽  
Reid Tingley ◽  
Brad Peori ◽  
Keith Vaughan
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Diazonium Salt ◽  
Mass Measurement ◽  
Aromatic Proton ◽  
2D Nmr ◽  
2D Nmr Spectroscopy ◽  
Piperazine Ring ◽  
Methylene Groups ◽  
Type 3

A series of 1,4-di-[2-aryl-1-diazenyl]-2-methylpiperazines (4a–n) have been synthesized by the reaction of 2-methylpiperazine with 2 equiv. of the appropriate diazonium salt. The products have been characterized by IR and NMR spectroscopy, and the molecular composition has been verified by HR-EIMS, with accurate mass measurement of the molecular ion. The presence of a chiral centre at C2 of the piperazine ring in the bistriazene 4 creates a multitude of diastereotopic protons in the methylene groups of the piperazine ring, as evidenced by the complexity of the NMR spectra, which nevertheless can be fully assigned in some cases, such as the tolyl- (4h) and phenyl- (4j) derivatives. These two compounds also show a discrimination between the two N-arydiazenyl groups, as evidenced by the doubling of several aromatic-carbon signals in the 13C NMR spectra. The assignment of the proton and carbon signals in 4h and 4j has been aided by the use of 2D NMR spectroscopy. A DEPT spectrum of 4j clearly discriminates the methylene carbons and also indicates the methine carbons of the piperazine ring. COSY spectra provide clear information about the interactions between diastereotopic protons; when these results are combined with the results of HSQC spectroscopy, the proton and carbon signals can be fully correlated, leading to an unequivocal assignment of the proton and carbon atoms of the piperazine ring. The HSQC spectrum of 4j also gives a complete correlation of the aromatic-proton and -carbon signals. These results compare favorably with the previously reported assignments of proton and carbon signals for triazenes of type 1 and bistriazenes of type 3.Key words: triazene, bistriazene, piperazine, 2-methylpiperazine, diastereotopic protons, diazonium coupling, 2D NMR, COSY, DEPT, HSQC.

Triazene derivatives of (1,x)-diazacycloalkanes. Part III. Synthesis and characterization of a series of 1,4-di[2-aryl-1-diazenyl]piperazines

2005 ◽  
Vol 83 (5) ◽  
pp. 471-476 ◽  
Author(s):  
Vanessa Renée Little ◽  
Reid Tingley ◽  
Keith Vaughan
Keyword(s):  
Mass Measurement ◽  
Variable Temperature ◽  
Molar Ratio ◽  
Diazonium Salts ◽  
Piperazine Ring ◽  
Nmr Data ◽  
Ir And Nmr Spectroscopy ◽  
Reported Data ◽  
Derivatives Of

Reaction of a series of diazonium salts with piperazine in a 2:1 molar ratio affords excellent yields of the 1,4-di-[2-aryl-1-diazenyl]piperazines (3), which have been characterized by IR and NMR spectroscopy. Structural characterization is supported by elemental analysis or by mass spectrometry with accurate mass measurement of the molecular ion. The protons of the piperazine ring hydrogens give rise to a sharp singlet at ca. 4 ppm in the NMR spectra, indicating that the conformational equilibrium in the piperazine ring is rapid on the NMR timescale. The four equivalent carbon atoms of the piperazine ring resonate in the range 46–48 ppm. A variable temperature NMR experiment suggests that there is restricted rotation around the N2—N3 bond of the triazene moiety in 3. The NMR data compares favorably with previous reported data for 1-aryldiazenyl-4-methylpiperazines (1) and 1,4-di-(2-aryldiazen-1-yl)homopiperazines (2b).Key words: triazene, piperazine, diazonium coupling, NMR.

Triazene derivatives of (1,x)-diazacycloalkanes. Part V.1 Synthesis and characterization of 4-ethyl-3-({6-ethyl-3-[2-aryl-1-diazenyl]hexahydro-1-pyrimidinyl}methyl)-1-[2-aryl-1-diazenyl)hexa- hydropyrimidines from the reaction of diazonium salts with mixtures of formaldehyde and 1,3-diaminopentane

2005 ◽  
Vol 83 (10) ◽  
pp. 1799-1807 ◽  
Author(s):  
Reid Tingley ◽  
M Brad Peori ◽  
Ryan Church ◽  
Keith Vaughan
Keyword(s):  
Diazonium Salts ◽  
X Ray Crystallography ◽  
Ir And Nmr Spectroscopy ◽  
New Compounds ◽  
Bicyclic Molecules ◽  
Derivatives Of ◽  
Methylene Group ◽  
Single Bonds

A new series of bistriazenes has been synthesized from a general reaction of diazonium salts with a mixture of 1,3-diaminopentane (DYTEK® EP diamine) and formaldehyde, which affords the 4-ethyl-3-({6-ethyl-3-[2-aryl-1-diazenyl]hexahydro-1-pyrimidinyl}methyl)-1-[2-aryl-1-diazenyl]hexahydropyrimidines (1). Each of the molecules of type 1 is built up of two equivalent 3-(aryldiazenyl)-6-ethylhexahydro-1-pyrimidinyl groups attached to a central methylene group. The importance of this study is in part due to the fact that the formaldehyde–1,3-diaminopentane system has not previously been investigated. All new compounds have been characterized by IR and NMR spectroscopy, with elemental analysis for selected compounds; one example from the series has been unequivocally characterized by X-ray crystallography. Although analysis of the NMR spectra is made somewhat difficult because of broadness and coalescence of signals due to the rotational dynamics of the N—N single bonds, it is possible to fully assign the proton spectra of all compounds and to detect 94% of all carbon signals. The fine structure within the proton spectra illustrate the diastereotopic nature of the methylene group protons because of the presence of a stereocenter in each hexahydropyrimidine ring. The general conclusion of this study is that alkanediamines with three carbon atoms in the spacer link between the nitrogen atoms give rise to the linear bicyclic molecules of type 1, 2, and 3, in contrast to the case of ethylenediamine (spacer link has two carbon atoms), which affords molecules of type 7 that exemplify the bridged bicyclic bistriazene structure. The new compounds of series 1 represent an extension of a broad ranging study of the synthesis of new bistriazene derivatives of (1,x)-diazacycloalkanes.Key words: triazene, diazonium coupling, hexahydropyrimidine, diaminopentane, diazacycloalkanes, stereocenter, diastereotopic protons.

Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

2004 ◽  
Vol 82 (8) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vanessa Renée Little ◽  
Keith Vaughan
Keyword(s):  
Free Energy ◽  
Chemical Shifts ◽  
Linear Free Energy Relationship ◽  
Piperazine Ring ◽  
Linear Free Energy ◽  
In Series ◽  
Methylene Groups ◽  
Diazonium Coupling ◽  
The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

Structural characterization of milled wood lignins from different eucalypt species

Holzforschung ◽  
2008 ◽  
Vol 62 (5) ◽  
Author(s):  
Jorge Rencoret ◽  
Gisela Marques ◽  
Ana Gutiérrez ◽  
David Ibarra ◽  
Jiebing Li ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Chemical Structure ◽  
2D Nmr ◽  
Analytical Pyrolysis ◽  
Additional Information ◽  
Diaryl Ether ◽  
Heteronuclear Single Quantum Correlation ◽  
Relative Abundances ◽  
Type 3

Abstract The chemical structure of milled-wood lignins from Eucalyptus globulus, E. nitens, E. maidenii, E. grandis, and E. dunnii was investigated. The lignins were characterized by analytical pyrolysis, thioacidolysis, and 2D-NMR that confirmed the predominance of syringyl over guaiacyl units and only showed traces of p-hydroxyphenyl units. E. globulus lignin had the highest syringyl content. The heteronuclear single quantum correlation (HSQC) NMR spectra yielded information about relative abundances of inter-unit linkages in the whole polymer. All the lignins showed a predominance of β-O-4′ ether linkages (66–72% of total side-chains), followed by β-β′ resinol-type linkages (16–19%) and lower amounts of β-5′ phenylcoumaran-type (3–7%) and β-1′ spirodienone-type linkages (1–4%). The analysis of desulfurated thioacidolysis dimers provided additional information on the relative abundances of the various carbon-carbon and diaryl ether bonds, and the type of units (syringyl or guaiacyl) involved in each of the above linkage types. Interestingly, 93–94% of the total β-β′ dimers included two syringyl units indicating that most of the β-β′ substructures identified in the HSQC spectra were of the syringaresinol type. Moreover, three isomers of a major trimeric compound were found which were tentatively identified as arising from a β-β′ syringaresinol substructure attached to a guaiacyl unit through a 4-O-5′ linkage.

scholarly journals Characterization of cDNAs encoding isoforms of hamster 3 beta-hydroxysteroid dehydrogenase/delta 5-->4 isomerase

1998 ◽  
Vol 20 (1) ◽  
pp. 99-110 ◽  
Author(s):  
FM Rogerson ◽  
J Courtemanche ◽  
A Fleury ◽  
JG LeHoux ◽  
JI Mason ◽  
...  
Keyword(s):  
Hydroxysteroid Dehydrogenase ◽  
Cdna Libraries ◽  
Sexually Dimorphic ◽  
High Affinity ◽  
Liver And Kidney ◽  
Low Levels ◽  
Type 3

Western blot analyses of various hamster tissues reveal high levels of expression of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in adrenal and liver, and moderate levels of expression in kidney. The expression in liver is sexually dimorphic; very high levels of protein are observed in adult male liver but very low levels are seen in the female liver. Three distinct cDNAs encoding isoforms of 3 beta-HSD were isolated from hamster cDNA libraries. The type 1 isoform is a high-affinity dehydrogenase/isomerase expressed in adrenal and male kidney. The type 2 isoform is also a high-affinity dehydrogenase/isomerase expressed in kidney and male liver. The type 3 enzyme is a 3-ketosteroid reductase expressed predominantly in kidney. Sequencing of the clones showed that all three are structurally very similar, although types 1 and 2 share the greatest degree of similarity. Immunohistochemical staining for 3 beta-HSD in the adrenal was found throughout the adrenal cortex. In the kidney staining was confined to tubules, and in the liver, heavy staining was found in hepatocytes. The cloning of cDNAs for 3 beta-HSD from the liver and kidney should help in elucidating the function of this enzyme in these tissues.

Triazene derivatives of (1,x)-diazacycloalkanes. Part VII. Synthesis of a series of 1-aryl-2-[3-(3-[2-aryl-1-diazenyl]-1,3-diazepan-1-ylmethyl)-1,3-diazepan-1-yl]-1-diazenes from the reaction of diazonium salts with mixtures of formaldehyde and 1,4-diaminobutane

2006 ◽  
Vol 84 (10) ◽  
pp. 1434-1441
Author(s):  
Reid Tingley ◽  
Keith Vaughan
Keyword(s):  
Diazonium Salt ◽  
Diazonium Salts ◽  
The Novel ◽  
Cage Structure ◽  
X Ray Crystallography ◽  
New Compounds ◽  
Type 3 ◽  
Bicyclic Molecules

A new series of bistriazenes, the 1-aryl-2-[3-(3-[2-aryl-1-diazenyl]-1,3-diazepan-1-ylmethyl)-1,3-diazepan-1-yl]-1-diazenes (8), has been synthesized from the reaction of diazonium salts with a mixture of 1,4-diaminobutane and formaldehyde. All new compounds of series 8 have been characterized by IR and NMR spectroscopy, and the elemental composition of selected examples has been verified by elemental analysis. The connectivity of the series has been unequivocally determined by X-ray crystallography. The new bistriazenes are important because the structure contains the novel saturated heterocycle, 1,3-diazepane. The general conclusion of this study is that alkanediamines with three or four carbon atoms in the spacer link between the nitrogen atoms give rise to the linear bicyclic molecules of type 2, in contrast to the case of ethylenediamine (two carbon atoms in spacer link), which affords molecules of type 3, which exemplify the cage structure of type 1.Key words: diazonium salt, triazene, bistriazene, diazepane, formaldehyde, nuclear magnetic resonance.

scholarly journals Novel LinA Type 3 δ-Hexachlorocyclohexane Dehydrochlorinase

2015 ◽  
Vol 81 (21) ◽  
pp. 7553-7559 ◽  
Author(s):  
Nidhi Shrivastava ◽  
Zbynek Prokop ◽  
Ashwani Kumar
Keyword(s):  
Amino Acid ◽  
Primary Structure ◽  
Degradation Pathway ◽  
Amino Acid Residues ◽  
Hch Isomers ◽  
New Variant ◽  
Type 3

ABSTRACTLinA is the first enzyme of the microbial degradation pathway of a chlorinated insecticide, hexachlorocyclohexane (HCH), and mediates the dehydrochlorination of α-, γ-, and δ-HCH. Its two variants, LinA type 1 and LinA type 2, which differ at 10 out of 156 amino acid residues, have been described. Their activities for the metabolism of different HCH isomers differ considerably but overall are high for γ-HCH, moderate for α-HCH, low for δ-HCH, and lacking for β-HCH. Here, we describe the characterization of a new variant of this enzyme, LinA type 3, whose gene was identified from the metagenome of an HCH-contaminated soil sample. Its deduced primary structure in the region spanning amino acid residues 1 to 147 of the protein exhibits 17 and 12 differences from LinA type 1 and LinA type 2, respectively. In addition, the residues GIHFAPS, present at the region spanning residues 148 to 154 in both LinA type 1 and LinA type 2, are deleted in LinA type 3.The activity of LinA type 3 for the metabolism of δ-HCH is several orders of magnitude higher than that of LinA type 1 or LinA type 2 and can be useful for improvement of the metabolism of δ-HCH.

scholarly journals Characterization of an infectious cDNA copy of the genome of a naturally occurring, avirulent coxsackievirus B3 clinical isolate

2005 ◽  
Vol 86 (1) ◽  
pp. 197-210 ◽  
Author(s):  
C.-K. Lee ◽  
K. Kono ◽  
E. Haas ◽  
K.-S. Kim ◽  
K. M. Drescher ◽  
...  
Keyword(s):  
Avirulent Strain ◽  
Cdna Copy ◽  
Naturally Occurring ◽  
Pathogenic Virus ◽  
Phenotype Comparison ◽  
Group B ◽  
Type 3 ◽  
Virus Strains

Group B coxsackieviruses (CVB) cause numerous diseases, including myocarditis, pancreatitis, aseptic meningitis and possibly type 1 diabetes. To date, infectious cDNA copies of CVB type 3 (CVB3) genomes have all been derived from pathogenic virus strains. An infectious cDNA copy of the well-characterized, non-pathogenic CVB3 strain GA genome was cloned in order to facilitate mapping of the CVB genes that influence expression of a virulence phenotype. Comparison of the sequence of the parental CVB3/GA population, derived by direct RT-PCR-mediated sequence analysis, to that of the infectious CVB3/GA progeny genome demonstrated that an authentic copy was cloned; numerous differences were observed in coding and non-coding sequences relative to other CVB3 strains. Progeny CVB3/GA replicated similarly to the parental strain in three different cell cultures and was avirulent when inoculated into mice, causing neither pancreatitis nor myocarditis. Inoculation of mice with CVB3/GA protected mice completely against myocarditis and pancreatitis induced by cardiovirulent CVB3 challenge. The secondary structure predicted for the CVB3/GA domain II, a region within the 5′ non-translated region that is implicated as a key site affecting the expression of a cardiovirulent phenotype, differs from those predicted for cardiovirulent and pancreovirulent CVB3 strains. This is the first report characterizing a cloned CVB3 genome from an avirulent strain.

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