ChemInform Abstract: 4-Azapteridines. Part 2. Spectral, Chromatographic and X-Ray Crystallographic Studies Concerning the Mode of Covalent Addition to the Pyrazino[2,3-e]-as-triazine Ring System.

1986 ◽  
Vol 17 (36) ◽  
Author(s):  
C.-C. TZENG ◽  
U. RVCHLEWSKA ◽  
D. J. HODGSON ◽  
R. P. PANZICA
Keyword(s):  
Ring System ◽  
Triazine Ring ◽  
X Ray

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>

An Intramolecular Boron Nitrogen Lewis Acid Base Pair on a Rigid Naphthyl Backbone

2012 ◽  
Vol 67 (6) ◽  
pp. 589-593 ◽  
Author(s):  
Daniel Winkelhaus ◽  
Beate Neumann ◽  
Norbert W. Mitzel
Keyword(s):  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Lewis Acid ◽  
Elemental Analysis ◽  
Base Pair ◽  
Ring System ◽  
X Ray Diffraction ◽  
Acid Base ◽  
X Ray ◽  
Boron Nitrogen

The reaction of (C6F5)2BCl with 8-lithio-N,N-dimethyl-1-naphthylamine (1) afforded the fivemembered ring system 8-bis(pentafluorophenyl)boryl-N,N-dimethyl-1-naphthylamine (2) with an intramolecular dative B-N bond. The compound was characterised by elemental analysis, NMR spectroscopy and single-crystal X-ray diffraction.

Cytochalasan Alkaloids as TRAIL Sensitizers from an Endophytic Fungus Chaetomium sp.

Planta Medica ◽  
2021 ◽  
Author(s):  
Hanli Ruan ◽  
Ying Gao ◽  
Ruihua Mao ◽  
Ye Liu ◽  
Ming Zhou
Keyword(s):  
Colorectal Cancer ◽  
Absolute Configuration ◽  
Endophytic Fungus ◽  
Cancer Cell Line ◽  
Ring System ◽  
Ht29 Cell ◽  
Colorectal Cancer Cell Line ◽  
X Ray ◽  
Fibrous Roots ◽  
Trail Sensitivity

Two new cytochalasans with a rare 6/6/5/5/7 pentacyclic ring system, named chaetoconvosins C−D (1−2), together with two known congeners (3−4), were isolated from the fermentation of an endophytic fungus, Chaetomium sp. SG-01, harbored in the fibrous roots of Schisandra glaucescens Diels. Their structures including the absolute configuration were elucidated by extensive spectroscopic (HRESIMS, NMR, and ECD) and X-ray crystallographic analyses. The TRAIL sensitivity of 1–4 in a TRAIL-resistant HT29 colorectal cancer cell line was evaluated, which revealed that co-treatment of 1–4 at 50 µM with TRAIL (150 ng/mL) reduced the HT29 cell viability by 19.0%, 24.1%, 17.9%, and 15.5%, respectively, compared to treatment with 1–4 alone.

scholarly journals Aspergiloid I, an unprecedented spirolactone norditerpenoid from the plant-derived endophytic fungus Aspergillus sp. YXf3

2014 ◽  
Vol 10 ◽  
pp. 2677-2682 ◽  
Author(s):  
Zhi Kai Guo ◽  
Rong Wang ◽  
Wei Huang ◽  
Xiao Nian Li ◽  
Rong Jiang ◽  
...  
Keyword(s):  
Endophytic Fungus ◽  
Spectroscopic Data ◽  
Biosynthetic Pathway ◽  
Culture Broth ◽  
Ring System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anti Oxidant ◽  
Inhibitory Activities ◽  
Aspergillus Sp

An unusual C18 norditerpenoid, aspergiloid I (1), was isolated from the culture broth of Aspergillus sp. YXf3, an endophytic fungus derived from Ginkgo biloba. Its structure was unambiguously established by analysis of HRMS–ESI and spectroscopic data, and the absolute configuration was determined by low-temperature (100 K) single crystal X-ray diffraction with Cu Kα radiation. This compound is structurally characterized by a new carbon skeleton with an unprecedented 6/5/6 tricyclic ring system bearing an α,β-unsaturated spirolactone moiety in ring B, and represents a new subclass of norditerpenoid, the skeleton of which is named aspergilane. The hypothetical biosynthetic pathway for 1 was also proposed. The cytotoxic, antimicrobial, anti-oxidant and enzyme inhibitory activities of 1 were evaluated.

scholarly journals NMR Investigation of the Copper(II)-Ciprofloxacin System

1999 ◽  
Vol 6 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Iztok Turel ◽  
Janez Košmrlj ◽  
Bjørn Andersen ◽  
Einar Sletten
Keyword(s):  
Acidic Medium ◽  
Acidic Solution ◽  
Relaxation Times ◽  
Ring System ◽  
Proton Relaxation ◽  
X Ray ◽  
Ph Values ◽  
Nmr Study ◽  
Terminal Nitrogen Atom ◽  
Titration Data

A proton NMR study was performed on the copper(ll)-ciprofloxacin system. The proton relaxation times (T1) were determined from the titration data in acidic and basic media. In acidic medium the H5 signal is dramatically affected and it is assumed that copper is bonded to the quinolone through carbonyl and one of the carboxyl oxygens. Such bonding is in agreement with the X-ray literature data for the complex [Cu(cf)2]Cl2.6H2O isolated from the slightly acidic solution. There are additional significant changes in T1 of H3′ and H5′ atoms which suggest that the terminal nitrogen atom of the piperazine ring system-N4′ also interacts with copper in the basic conditions. Thus it is plausible that more than one species are present in the solution at high pH values.

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