Synthesis and conformational analysis of 2-amino-1,2,3,4-tetrahydro-1-naphthalenols

1988 ◽  
Vol 66 (3) ◽  
pp. 517-527 ◽  
Author(s):  
Antonio Delgado ◽  
José Miguel Garcia ◽  
David Mauleon ◽  
Cristina Minguillon ◽  
Joan Ramon Subirats ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nitrogen Atom ◽  
Conformational Analysis ◽  
Theoretical Calculations ◽  
The Other ◽  
Experimental Conditions ◽  
High Yields ◽  
Hydrolysis Of ◽  
Major Conformation

Synthesis and conformational analysis of several cis- and (or) trans-2-amino-1,2,3,4-tetrahydro-1-naphthalenols are described. Introduction of the nitrogen atom at the C(2) position of the starting tetralones 3 has been carried out through nitrosation followed by reduction of the intermediate hydroxyimino tetralone and (or) Neber rearrangement of the tosyloxy derivatives 7a–e. Stereoselective reduction of the C(1) carbonyl group of acetamidotetralones 5a–e or aminotetralones 8a–e afforded the corresponding acetamido or aminotetralols, respectively, of OH/N trans stereochemistry whereas an opposite stereoselectivity was observed in reduction of C(8)-OCH3 derivatives 5f and 8f under the same experimental conditions. Finally, acid hydrolysis of trans-acetamidotetralols led to cis-aminoalcohols in high yields. Conformational analysis has been carried out by 1H nuclear magnetic resonance techniques and MM2 theoretical calculations. All cis derivatives showed a major conformation in which the C(1)-OH group adopts a pseudoaxial disposition. On the other hand, trans-aminoalcohols in CDCl3 showed a major or exclusive OH/N trans-dipseudoequatorial conformation in which stabilization by intramolecular OH/N hydrogen bonding is possible. The only exception was found in C(8)-OCH3trans-aminoalcohols in DMSO-d6 solution, which showed a major OH/N trans-diaxial conformation.

Alkaloids of the Australian Apocynaceae: Kopsia longiflora Merr. III. Preliminary Degradation of the Alkaloids

1962 ◽  
Vol 15 (1) ◽  
pp. 130 ◽  
Author(s):  
WD Crow ◽  
M Michael
Keyword(s):  
Nitrogen Atom ◽  
Oxygen Atom ◽  
Alkaline Hydrolysis ◽  
The Other ◽  
Partial Hydrolysis ◽  
Residual Oxygen ◽  
Methoxycarbonyl Group ◽  
Additional Oxygen Atom ◽  
Hydrolysis Of ◽  
Aromatic Ether

Graded alkaline hydrolysis of the monoacid tertiary bases kopsiflorine (C23H28O5N2), kopsilongine (C24H30O6N2), and kopsamine (C24H28O7N2) shows that they contain two methoxycarbonyl groups. All but one of the residual oxygen atoms are accounted for as aromatic ether linkages. One of the methoxycarbonyl groups is responsible for the deactivation of the other nitrogen atom (N(a)) present, since anew basic centre is generated by partial hydrolysis and subsequent decarboxylation of the acid produced. The alkaloids are tentatively formulated as blocked indoline bases containing a urethane grouping at N(a). The fourth alkaloid, kopsinine (C21H26O2N2) is similarly formulated, but in this case N(a) is weakly basic, the urethane methoxycarbonyl group and the additional oxygen atom being absent.

Formation of methyl 2-arylhydrazono-3-oxobutanoates and 2-arylhydrazono-3-oxobutanenitriles during the coupling reaction of arenediazonium ions with methyl 3-aminocrotonate and 3-aminocrotononitrile

1995 ◽  
Vol 73 (2) ◽  
pp. 169-175 ◽  
Author(s):  
D. Sean Brown ◽  
Jason V. Jollimore ◽  
Marcus P. Merrin ◽  
Keith Vaughan ◽  
Donald L. Hooper
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Coupling Reaction ◽  
Coupling Reactions ◽  
Diazonium Coupling ◽  
High Yields ◽  
Hydrolysis Of ◽  
C Nmr

Reaction of aryldiazonium salts with methyl 3-aminocrotonate (1) affords high yields of the methyl 2-arylhydrazono-3-oxobutanoates (4); analogous diazonium coupling with 3-aminocrotononitrile (2) gives the 2-arylhydrazono-3-oxobutanenitriles (5). The hydrazones are the product of diazonium coupling at the C2-vinylic carbon, concomitant with hydrolysis of the 3-amino substituent to the 3-oxo derivative; there is no evidence for the formation of a triazene (6), which would be the product of N-coupling. All hydrazones (4a–e and 5a–d) have been fully characterized by IR and 1H and 13C NMR spectroscopy; the NMR spectra of the methyl 2-arylhydrazono-3-oxobutanoates (4) suggest the presence of two isomeric intramolecularly H-bonded forms in solution. Selected compounds were further characterized by elemental analysis and mass spectrometry. A mechanism is proposed for the conversion of 1 or 2 into 4 or 5, and these observations are compared with previously reported observations of diazonium coupling reactions with unsaturated systems. Keywords: hydrazone, diazonium, aminocrotonate, aminocrotononitrile, hydrogen bonding.

scholarly journals Crystal structure of hexa-μ-chlorido-μ4-oxido-tetrakis{[1-(2-hydroxyethyl)-2-methyl-5-nitro-1H-imidazole-κN 3]copper(II)} containing short NO2...NO2 contacts

2019 ◽  
Vol 75 (7) ◽  
pp. 1057-1060
Author(s):  
Ja-Shin Wu ◽  
Daniel G. Shlian ◽  
Joshua H. Palmer ◽  
Rita K. Upmacis
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Nitrogen Atom ◽  
Copper Complex ◽  
Chloride Ions ◽  
The Other ◽  
Acta Cryst ◽  
Trigonal Bipyramidal ◽  
Scattering Contribution ◽  
Solvent Molecules

The title tetranuclear copper complex, [Cu4Cl6O(C6H9N3O3)4] or [Cu4Cl6O(MET)4] [MET is 1-(2-hydroxyethyl)-2-methyl-5-nitro-1H-imidazole or metronidazole], contains a tetrahedral arrangement of copper(II) ions. Each copper atom is also linked to the other three copper atoms in the tetrahedron via bridging chloride ions. A fifth coordination position on each metal atom is occupied by a nitrogen atom of the monodentate MET ligand. The result is a distorted CuCl3NO trigonal–bipyramidal coordination polyhedron with the axial positions occupied by oxygen and nitrogen atoms. The extended structure displays O—H...O hydrogen bonding, as well as unusual short O...N interactions [2.775 (4) Å] between the nitro groups of adjacent clusters that are oriented perpendicular to each other. The scattering contribution of disordered water and methanol solvent molecules was removed using the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9–16] in PLATON [Spek (2009). Acta Cryst. D65, 148–155].

Relative Intensities in ED Patterns From Thin Gold Films

1972 ◽  
Vol 30 ◽  
pp. 636-637
Author(s):  
R. H. Morriss ◽  
J. D. C. Peng ◽  
C. D. Melvin
Keyword(s):  
Theoretical Calculations ◽  
Diffraction Theory ◽  
Gold Films ◽  
Reasonable Accuracy ◽  
Experimental Conditions ◽  
Crystal Perfection ◽  
Heavy Atoms ◽  
Fine Focus ◽  
Convergent Beam ◽  
Beam Diffraction

Although dynamical diffraction theory was modified for electrons by Bethe in 1928, relatively few calculations have been carried out because of computational difficulties. Even fewer attempts have been made to correlate experimental data with theoretical calculations. The experimental conditions are indeed stringent - not only is a knowledge of crystal perfection, morphology, and orientation necessary, but other factors such as specimen contamination are important and must be carefully controlled. The experimental method of fine-focus convergent-beam electron diffraction has been successfully applied by Goodman and Lehmpfuhl to single crystals of MgO containing light atoms and more recently by Lynch to single crystalline (111) gold films which contain heavy atoms. In both experiments intensity distributions were calculated using the multislice method of n-beam diffraction theory. In order to obtain reasonable accuracy Lynch found it necessary to include 139 beams in the calculations for gold with all but 43 corresponding to beams out of the [111] zone.

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

Polar Diels-Alder Reactions Under Microwave Irradiation Employing Different Heterocyclic Compounds as Electrophiles

2019 ◽  
Vol 16 (6) ◽  
pp. 527-543 ◽  
Author(s):  
Pedro M.E. Mancini ◽  
Carla M. Ormachea ◽  
María N. Kneeteman
Keyword(s):  
Organic Synthesis ◽  
Heterocyclic Compounds ◽  
Ionic Conduction ◽  
Theoretical Calculations ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
The Other ◽  
Conventional Heating ◽  
Protic Ionic Liquids ◽  
Solvent Free Conditions

During the last twenty years, our research group has been working with aromatic nitrosubstituted compounds acting as electrophiles in Polar Diels-Alder (P-DA) reactions with different dienes of diverse nucleophilicity. In this type of reaction, after the cycloaddition reaction, the nitrated compounds obtained as the [4+2] cycloadducts suffer cis-extrusion with the loss of nitrous acid and a subsequent aromatization. In this form, the reaction results are irreversible. On the other hand, the microwave-assisted controlled heating become a powerful tool in organic synthesis as it makes the reaction mixture undergo heating by a combination of thermal effects, dipolar polarization and ionic conduction. As the Diels-Alder (D-A) reaction is one of the most important process in organic synthesis, the microwave (MW) irradiation was applied instead of conventional heating, and this resulted in better yields and shorter reaction times. Several substituted heterocyclic compounds were used as electrophiles and different dienes as nucleophiles. Two experimental situations are involved: one in the presence of Protic Ionic Liquids (PILs) as solvent and the other under solvent-free conditions. The analysis is based on experimental data and theoretical calculations.

The effect of cation concentration on the nitrogen splitting constant of nitroxide free radicals

1990 ◽  
Vol 55 (10) ◽  
pp. 2377-2380
Author(s):  
Hamza A. Hussain
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Bonding ◽  
Free Radicals ◽  
Esr Spectroscopy ◽  
The Other ◽  
Tetraethylammonium Bromide ◽  
Splitting Constant ◽  
The One ◽  
Positively Charged ◽  
Two Equilibria

Nitroxide free radicals prepared from diethylamine, piperidine and pyrrolidine by oxidation with hydrogen peroxide were studied by ESR spectroscopy. The changes in the 14N splitting constant (aN) caused by the addition of KBr or tetraethylammonium bromide were measured in dependence on the concentration of the ions. For diethylamine nitroxide and piperidine nitroxide, the results are discussed in terms of two equilibria: the one, involving the anion, is associated with a gain or loss of hydrogen bonds to the nitroxide oxygen atom, the other is associated with the formation of solvent shared units involving the cation, which results in changes in the hydrogen bonding strenght. The large increase in the aN value in the case of pyrrolidine nitroxide is explained in terms of an interaction from one side of the positively charged N atom; the increase in aN in the case of diethylamine and piperidine nitroxides is explained in terms of interactions with both sides of the positively charged N atom.

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