scholarly journals C4–C5 fused pyrazol-3-amines: when the degree of unsaturation and electronic characteristics of the fused ring controls regioselectivity in Ullmann and acylation reactions

2020 ◽  
Vol 18 (27) ◽  
pp. 5145-5156
Author(s):  
Elisabeth Bou-Petit ◽  
Arnau Plans ◽  
Nieves Rodríguez-Picazo ◽  
Antoni Torres-Coll ◽  
Cristina Puigjaner ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Dft Calculations ◽  
Degree Of Unsaturation ◽  
Fused Ring ◽  
Protonated Nitrogen Atom ◽  
Acylation Reactions

The regioselectivity of Ullmann and acylation reactions of C4–C5 fused pyrazol-3-amines is predicted using DFT calculations of the most stable tautomer (1H- or 2H-pyrazole) and occur, mainly, at the NH and non-protonated nitrogen atom, respectively.

On the microwave-assisted synthesis of acylphenothiazine derivatives — Experiment versus theory synergism

2010 ◽  
Vol 88 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Luiza Gaina ◽  
Dan Porumb ◽  
Ioan Silaghi-Dumitrescu ◽  
Castelia Cristea ◽  
Luminita Silaghi-Dumitrescu
Keyword(s):  
Molecular Modeling ◽  
Acetic Anhydride ◽  
Dft Calculations ◽  
Theoretical Explanation ◽  
Microwave Assisted Synthesis ◽  
Phenothiazine Derivatives ◽  
Microwave Assisted ◽  
Experiment Versus ◽  
Semi Empirical ◽  
Acylation Reactions

The microwave-assisted synthesis of a series of acylphenothiazine derivatives is described. 10H-Phenothiazine-3-carbaldehyde derivatives were obtained in moderate yields by the Duff formylation reaction, and 10-acetyl-phenothiazine derivatives were obtained in excellent yields by acetylating phenothiazine derivatives with acetic anhydride. A theoretical explanation for the chemoselectivity and regioselectivity of these acylation reactions applied to phenothiazine substrates was attempted by molecular-modeling analyses based on molecular mechanics, and semi-empirical and DFT calculations.

Crystal Structure of Bis[hexakis(dimethylamino)cyclotriphosphonitrilium] Tetrachlorocobaltate(II)

1974 ◽  
Vol 52 (5) ◽  
pp. 734-737 ◽  
Author(s):  
Alistair L. Macdonald ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Nitrogen Atom ◽  
Least Squares ◽  
Electron Density ◽  
Title Compound ◽  
Full Matrix ◽  
Space Group ◽  
Density Methods ◽  
Protonated Nitrogen Atom ◽  
Hydrogen Bonded

Crystals of the title compound, [N3P3(NMe2)6H]2CoCl4, are orthorhombic, a = 34.623, b = 13.964, c = 10.486 Å, Z = 4, space group P212121. The structure was determined by Patterson and electron-density methods and refined by full-matrix least-squares procedures to R = 0.088 for 2178 observed reflexions. Both rings are slightly non-planar, with three distinct pairs of NP bonds: commencing at the protonated nitrogen atom, 1.68, 1.56, and 1.58 Å. The CoCl42− ion is tetrahedral and is hydrogen bonded to both rings, N—H … Cl = 3.32, 3.36 Å.

Diastereoisomeric proton-bound complexes of 1,5-diaza-cis-decalin in the gas phase

2009 ◽  
Vol 74 (2) ◽  
pp. 243-254 ◽  
Author(s):  
Jana Roithová
Keyword(s):  
Mass Spectrometry ◽  
Nitrogen Atom ◽  
Dft Calculations ◽  
Electrospray Ionization ◽  
Gas Phase ◽  
Energy Difference ◽  
Ion Pair ◽  
Collision Induced Dissociation ◽  
Chiral Effects

Diastereoisomeric proton-bound complexes of 1,5-diaza-cis-decalin (1) with butan-2-amine (2) are studied by means of the DFT calculations and mass spectrometry. The calculations reveal that 2 is bound via proton to only one nitrogen atom of the bicyclic base 1. The homochiral complex is favored by about 4 kJ/mol over the heterochiral complex. For a more loosely bound ion-pair complex [(1H)I(2H)]+ of the protonated bases 1 and 2 with an iodine counterion the energy difference drops to about 2 kJ/mol. Chiral effects in the formation of [(1)H(2)]+ are studied by the collision-induced dissociation of [(1H)I(2H)]+ generated by the electrospray ionization of the solution of [1·Cu(OH)I] and 2 in acetonitrile. The dominant fragmentation of [(1H)I(2H)]+ leads to 1·H+ and 2·HI, which is at small collision energies accompanied by the elimination of HI leading to the desired [(1)H(2)]+ ion. The chiral effect of 1.2 is determined in favor for the formation of the homochiral complex [(1)H(2)]+.

scholarly journals Coordination isomerism in N-heterocyclic phosphenium thiocyanates

2018 ◽  
Vol 96 (6) ◽  
pp. 549-554 ◽  
Author(s):  
Markus Blum ◽  
Jacqueline Gebhardt ◽  
Marius Papendick ◽  
Simon H. Schlindwein ◽  
Martin Nieger ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Nitrogen Atom ◽  
Coordination Polymer ◽  
Dft Calculations ◽  
Ion Pair ◽  
The Other ◽  
Single Bond ◽  
One Dimensional ◽  
Structural Differences ◽  
The Individual

Two N-heterocyclic phosphines with exocyclic SCN substituents were synthesised via metathesis of chlorophosphine precursors with KSCN and fully characterised. The crystallographic studies reveal that the products exhibit pronounced structural differences. The thiocyanato unit binds in one case via the nitrogen atom to yield a molecular structure with a slightly elongated P–N single bond and, in the other case, via the sulfur atom to form a structure that is best described as an ion pair and forms a one-dimensional coordination polymer in the crystal. DFT calculations suggest that the P–N and P…S interactions can be described as covalent and dative bonds, respectively, and that the structural differences correlate with the different cation stabilities of the individual phosphenium cation fragments.

scholarly journals Protonen on Tour – DFT-Studie zur H+-Wanderung in [1.1.1]- und [2.2.2]-Cryptanden / Protons on Tour – DFT-study of H+-Migration in [1.1.1]- and [2.2.2]-Cryptands

2006 ◽  
Vol 61 (11) ◽  
pp. 1327-1334 ◽  
Author(s):  
Ralph Puchta ◽  
Michael Galle ◽  
Nico J. R. van Eikema Hommes
Keyword(s):  
Activation Energy ◽  
Nitrogen Atom ◽  
Oxygen Atom ◽  
Dft Calculations ◽  
The Other ◽  
Dft Study ◽  
Ether Oxygen Atom ◽  
Ether Oxygen ◽  
Rule Out

DFT-calculations (RB3LYP/LANL2DZp) show that the migration of a proton inside [1.1.1]- and [2.2.2]-cryptand from one nitrogen atom to the other follows different paths. While the proton in [H⊂1.1.1]-cryptand moves via an ether oxygen atom (activation energy: 19.2 kcal/mol), the proton in [H⊂2.2.2]-cryptand moves directly from one nitrogenatom to the other (activation energy: 16.1 kcal/mol). Our calculations rule out the application of doubly protonated [2.2.2]-cryptands as anion hosts.

Synthesis and Preliminary Pharmacological Evaluation of 4′-Arylalkyl Analogues of Clozapine. III. Replacement of the Tricyclic Nucleus with a Bicyclic Template

2007 ◽  
Vol 60 (12) ◽  
pp. 928 ◽  
Author(s):  
Ben Capuano ◽  
Ian T. Crosby ◽  
Edward J. Lloyd ◽  
David A. Taylor
Keyword(s):  
Nitrogen Atom ◽  
Binding Affinity ◽  
Receptor Binding ◽  
Structural Characterization ◽  
Research Program ◽  
Substituent Effects ◽  
Bicyclic Compounds ◽  
Degree Of Unsaturation ◽  
Selection Of

As a continuing part of our research program in search of novel compounds for the treatment of schizophrenia, we report the synthesis and preliminary receptor binding affinity for a series of bicyclic analogues of clozapine derived from a selection of promising tricyclic candidates published previously. These bicyclic compounds investigate some substituent effects and the length and nature of the linker between an ionizable nitrogen atom at physiological pH and the introduced aryl moiety. The chemistry, structural characterization, and in vitro evaluation are described. Preliminary findings on the effects on activity of the nature and length of the linker, degree of unsaturation, and selected substituents coupled to the bicyclic nucleus are discussed in relation to affinity for dopamine D4 and serotonin 5-HT2A receptors.

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