Unusual Formation of New Indole-Containing Heterocyclic Ring Systems

1987 ◽  
Vol 40 (12) ◽  
pp. 1965 ◽  
Author(s):  
DS Black ◽  
N Chaichit ◽  
BM Gatehouse ◽  
GI Moss
Keyword(s):  
Aqueous Ammonia ◽  
Heterocyclic Ring ◽  
Ethyl Esters ◽  
Gaseous Ammonia ◽  
Ring Systems ◽  
X Ray ◽  
X Ray Crystallography ◽  
Unusual Formation

The oxazinoindoletrione (3) underwent reaction with aqueous ammonia in methanol or ethanol to yield the polycyclic methyl or ethyl esters (4) and (5) respectively. Reaction of trione (3) with gaseous ammonia in dry ethanol gave the aminobenzodiazepinone (7). This compound lost ammonia on heating in toluene to give compound (11) and in the presence of methanol or ethanol gave the methyl or ethyl esters (9) and (10) respectively. The structures of compounds (4), (7) and (10) were all established by X-ray crystallography.

scholarly journals 5-Amino-3-(diethylamino)-5H-benzo[4,5]imidazo[1,2-b][1,2,4,6]thiatriazine 1,1-Dioxide

Molbank ◽  
10.3390/m1018 ◽  
2018 ◽  
Vol 2018 (3) ◽  
pp. M1018
Author(s):  
Victor Tran ◽  
Craig Forsyth ◽  
Craig Francis
Keyword(s):  
Chemical Space ◽  
Heterocyclic Ring ◽  
Product Structure ◽  
Bioactive Molecules ◽  
Ring Systems ◽  
X Ray ◽  
X Ray Crystallography ◽  
Extended Range ◽  
Derivatives Of

In the quest for discovery of novel bioactive molecules, new heterocyclic ring systems provide templates for exploration of uncharted chemical space. Herein, we describe the synthesis of a new benzo[4,5]imidazo[1,2-b][1,2,4,6]thiatriazine derivative from readily available 1,2-diaminobenzimidazole and N,N-diethyl-N′-chlorosulfonyl chloroformamidine. The product structure, confirmed by X-ray crystallography, bears an exocyclic NH2 group, which should enable synthesis of an extended range of derivatives of this unusual scaffold.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

scholarly journals The influence of exocyclic lone pairs on the bonding and geometry of type A mesoionic rings

2021 ◽  
Author(s):  
Christopher Antony Ramsden ◽  
Wojciech Piotr Oziminski
Keyword(s):  
Ab Initio ◽  
Type A ◽  
Nbo Analysis ◽  
Ring Systems ◽  
X Ray ◽  
X Ray Crystallography ◽  
Bond Model ◽  
Lone Pairs ◽  
Mp2 Calculations ◽  
Good Agreement

AbstractBased on structures determined by X-ray crystallography, ab initio MP2 calculations on type A mesoionic rings give geometries in good agreement with observed values. A study of four mesoionic ring systems, each with exocyclic oxygen, nitrogen or carbon groups, shows that the presence and configuration of exocyclic lone pairs significantly influences the geometry and configurational preference. Using a localised bond model and NBO analysis, these effects are rationalised in terms of an anomeric interaction of lone pairs with the antibonding orbitals of adjacent σ bonds. In agreement with experiment, similar effects are calculated for pyran-2-imines.

Structure and nuclear magnetic resonance spectra of 6-bromo-3,3′,4′,5,7-penta-O-methylcatechin

1985 ◽  
Vol 63 (8) ◽  
pp. 2176-2180 ◽  
Author(s):  
F. W. B. Einstein ◽  
E. Kiehlmann ◽  
E. K. Wolowidnyk
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Title Compound ◽  
Bromine Atom ◽  
Heterocyclic Ring ◽  
Equatorial Orientation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Nuclear Magnetic Resonance Spectra ◽  
Ring Conformations

The title compound has been synthesized by selective debromination of 6,8-dibromocatechin and indirect methylation of the resulting 6-bromocatechin via its pentaacetate. The structure of C20H23BrO6 has been determined by X-ray crystallography. The compound crystallizes in the space group P1 with a = 9.589(3) Å, b = 11.576(3) Å, c = 11.326(3) Å, α = 118.80(3)°, β = 93.23(3)°, γ = 111.44(3)°, ρc = 1.481 g cm−3, and Z = 2. Intensities were measured for 2584 independent reflections (2θ < 45°) of which 2213 were observed (I > 3.0σ(I)) and used in subsequent refinement (final R values were R = 0.0268 and Rw = 0.0344). Crystallographic and pmr data confirm the position of the bromine atom at C-6, the trans-diaxial arrangement of H-2/H-3 and the quasi-equatorial orientation of the 3,4-dimethoxyphenyl group (ring B). The two heterocyclic ring conformations are consistent with the expected flexibility of the molecule.

scholarly journals Unusual formation of (E)-11-(aminomethylene)-8,9,10,11-tetrahydropyrido[2′,3′:4,5]pyrimido[1,2-a]azepin-5(7H)-one and its crystal structure

2017 ◽  
Vol 73 (10) ◽  
pp. 1497-1500
Author(s):  
Khamid U. Khodjaniyazov ◽  
Utkir S. Makhmudov ◽  
Kambarali K. Turgunov ◽  
Burkhon Z. Elmuradov
Keyword(s):  
Crystal Structure ◽  
Structural Analysis ◽  
Aqueous Ammonia ◽  
Boat Conformation ◽  
X Ray ◽  
First Time ◽  
Twist Boat ◽  
Unusual Formation

Selective C-formylation of 8,9,10,11-tetrahydropyrido[2′,3′:4,5]pyrimido[1,2-a]-azepin-5(7H)-one has been studied for the first time. It was revealed that formylation proceeds by the formation of an intermediate salt, which due to the re-amination process on treatment with aqueous ammonia transformed into the corresponding (E)-11-(aminomethylene)-8,9,10,11-tetrahydropyrido[2′,3′:4,5]-pyrimido[1,2-a]azepin-5(7H)-one, C13H14N4O, as anE-isomer. Formylation was carried out by Vilsmeier–Haack reagent and the structure of the synthesized compound was confirmed by X-ray structural analysis, spectroscopic and LC–MS methods. In the molecule, the seven-membered pentamethylene ring adopts a twist-boat conformation.

A complex of gallium with a Schiff base - bis(orthoquinone) ligand

1999 ◽  
Vol 77 (4) ◽  
pp. 502-510 ◽  
Author(s):  
Martyn A Brown ◽  
Jesus A Castro ◽  
Bruce R McGarvey ◽  
Dennis G Tuck
Keyword(s):  
Schiff Base ◽  
Liquid Ammonia ◽  
Aqueous Ammonia ◽  
Tridentate Ligand ◽  
Triclinic Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Spin Resonance ◽  
Aerial Oxidation ◽  
A Cell

The electrochemical oxidation of gallium in a cell containing a solution of 3,5-di-tert-butylcatechol (H2dbc) in a mixture of liquid ammonia and diethyl ether gives rise to the complex Ga(dbqdi)2, where dbqdi is a tridentate ligand formed by the condensation of two molecules of H2dbc and ammonia. The same paramagnetic molecule can be prepared by treating GaCl3 with H2dbc in ethanol with concentrated aqueous ammonia, with subsequent aerial oxidation. The crystal parameters are triclinic, space group P[Formula: see text], a = 11.6140(8), b = 12.3415(9), c = 20.765(1) Å, α = 89.491(1)°, β = 74.287(1)°, γ = 75.748(1)°, Z = 2, and R = 0.0542 for 7578 unique reflections. The structure, which is based on a GaO4N2 kernel, is discussed on the basis of crystallographic and ESR results.Key words: gallium, electrochemical synthesis, electron spin resonance, X-ray crystallography.

scholarly journals The influence of exocyclic lone pairs on the bonding and geometry of type A mesoionic rings

2021 ◽  
Author(s):  
Christopher Antony Ramsden ◽  
Wojciech Piotr Oziminski
Keyword(s):  
Ab Initio ◽  
Type A ◽  
Ring Systems ◽  
X Ray ◽  
X Ray Crystallography ◽  
Bond Model ◽  
Lone Pairs ◽  
Mp2 Calculations ◽  
Good Agreement

Abstract Based on structures determined by X-ray crystallography, ab initio MP2 calculations on type A mesoionic rings give geometries in good agreement with observed values. A study of four mesoionic ring systems, each with exocyclic oxygen, nitrogen or carbon groups, shows that the presence and configuration of exocyclic lone pairs significantly influences the geometry and configurational preference. Using a localised bond model, these effects are rationalised in terms of an anomeric interaction of lone pairs with the antibonding orbitals of adjacent σ bonds. In agreement with experiment, similar effects are calculated for pyran-2-imines.

ChemInform Abstract: Unusual Formation of New Indole-Containing Heterocyclic Ring Systems.

ChemInform ◽  
1988 ◽  
Vol 19 (14) ◽  
Author(s):  
D. ST. C. BLACK ◽  
N. CHAICHIT ◽  
B. M. GATEHOUSE ◽  
G. I. MOSS
Keyword(s):  
Heterocyclic Ring ◽  
Ring Systems ◽  
Unusual Formation

Preparation and X-ray crystal structures of the arsenic pentafluoride adducts of benzo-2,1,3-thiadiazole and benzo-1,2,3-thiadiazole

1986 ◽  
Vol 64 (5) ◽  
pp. 849-853 ◽  
Author(s):  
Allen Apblett ◽  
Tristram Chivers ◽  
John F. Richardson
Keyword(s):  
Nitrogen Atom ◽  
Crystal Structures ◽  
Benzene Ring ◽  
Heterocyclic Ring ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
C Nmr

The reaction of arsenic pentafluoride with benzo-2,1,3-thiadiazole, 1, or benzo-1,2,3-thiadiazole, 2, in liquid SO2 gave 1:1 adducts that were characterized spectroscopically (infrared and 13C nmr) and by X-ray crystallography. Crystal data: for 1•AsF5, monoclinic, space group P21/n, a = 6.932(1), b = 9.113(1), c = 15.136(2) Å, β = 98.035(7)°, V = 946.8(2) Å3, Z = 4; for 2•AsF5, monoclinic, space group P21/a, a = 7.573(2), b = 13.101(2), c = 9.514(3) Å, β = 90.95(2)°, V = 943.9(4) Å3, Z = 4. The coordination of AsF5 to one of the nitrogen atoms in 1 introduces asymmetry in the heterocyclic ring, with the longer bond lengths being associated with the coordinated nitrogen atom, d(S—N) = 1.633(5) and 1.577(6) Å, d(C—N) = 1.364(7) and 1.339(8) Å. The quinonoid character of the benzene ring is still apparent in the adduct. In 2•AsF5, the AsF5 molecule is coordinated to the nitrogen atom that is bonded to carbon.

scholarly journals Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

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