Synthesis and structural assignment of novel 5'-epimeric 3'-deoxy-3',4'-didehydronucleoside-5'-C-phosphonates

2011 ◽  
Author(s):  
Magdalena Petrová ◽  
Miloš Buděšínský ◽  
Blanka Klepetářová ◽  
Ivan Rosenberg
Keyword(s):  
Structural Assignment

Synthesis and Reactivity of Precolibactin 886

2019 ◽  
Author(s):  
Seth Herzon ◽  
Alan R. Healy ◽  
kevin wernke ◽  
Chung Sub Kim ◽  
Nicholas Lees ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Gene Cluster ◽  
Amino Alcohol ◽  
Biomimetic Synthesis ◽  
Cross Linking ◽  
E Coli ◽  
Hplc Purification ◽  
Structural Assignment ◽  
Biosynthetic Precursor ◽  
Double Oxidation

<div>The clb gene cluster encodes the biosynthesis of metabolites known as precolibactins and colibactins. The clb pathway is found in gut commensal E. coli, and clb metabolites are thought to initiate colorectal cancer via DNA cross-linking. Precolibactin 886 (1) is one of the most complex isolated clb metabolites; it contains a 15-atom macrocycle and an unusual 5-hydroxy-3-oxazoline ring. Here we report confirmation of the structural assignment via a biomimetic synthesis of precolibactin 886 (1) proceeding through the amino alcohol 9. Double oxidation of 9 afforded the unstable α-ketoimine 2 which underwent macrocyclization to precolibactin 886 (1) upon HPLC purification (3% from 9). Studies of the putative precolibactin 886 (1) biosynthetic precursor 2, the model α-ketoimine 25, and the α-dicarbonyl 26 revealed that these compounds are susceptible to nucleophilic rupture of the C36–C37 bond. Moreover, cleavage of 2 produces other known clb metabolites or biosynthetic intermediates. This unexpected reactivity explains the difficulties in isolating full clb metabolites and accounts for the structure of a recently identified colibactin–adenine adduct. The colibactin peptidase ClbP deacylates synthetic precolibactin 886 (1) to form a non-genotoxic pyridone, suggesting precolibactin 886 (1) lies off-path of the major biosynthetic route.</div>

Detailed 1H and 13C NMR structural assignment of three biologically active lignan lactones

2006 ◽  
Vol 63 (1) ◽  
pp. 234-239 ◽  
Author(s):  
Vladimir Constantino Gomes Heleno ◽  
Rosangela da Silva ◽  
Susimaire Pedersoli ◽  
Sérgio de Albuquerque ◽  
Jairo Kenupp Bastos ◽  
...  
Keyword(s):  
13C Nmr ◽  
Biologically Active ◽  
1H And 13C Nmr ◽  
Structural Assignment

scholarly journals Synthesis and Pharmacological Evaluation of 2-(4-Halosubstituted phenyl)-4,5-diphenyl-1H-imidazoles

2008 ◽  
Vol 5 (3) ◽  
pp. 447-452 ◽  
Author(s):  
G. Nagalakshmi
Keyword(s):  
Anticonvulsant Activity ◽  
Glacial Acetic Acid ◽  
Ammonium Acetate ◽  
Antiinflammatory Activity ◽  
Aromatic Aldehydes ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
H Nmr ◽  
Structural Assignment ◽  
Paw Oedema

In the present study, 2-(4-halosubstituted phenyl)-4,5-diphenyl-1Himidazoles have been synthesized by refluxing benzil and ammonium acetate with different 4-halosubstituted aromatic aldehydes in glacial acetic acid. The structural assignment of this compound has been made on the basis of elemental analysis, UV, IR,1H NMR and Mass spectral data. Toxicity of the compound has been determined. The synthesized compound was evaluated for antiinflammatory activity against carrageenan induced paw oedema and anticonvulsant activity against maximal electro-shock-induced convulsions in rats.

Structural Assignment of Polarization in Hydrogen-Bonded Supramolecular Ferroelectrics

2007 ◽  
Vol 129 (43) ◽  
pp. 12920-12921 ◽  
Author(s):  
Reiji Kumai ◽  
Sachio Horiuchi ◽  
Hajime Sagayama ◽  
Taka-hisa Arima ◽  
Masashi Watanabe ◽  
...  
Keyword(s):  
Structural Assignment ◽  
Hydrogen Bonded

Ethylboration of Stannyl-Substituted Sulfur Diimides

2001 ◽  
Vol 56 (4-5) ◽  
pp. 342-346 ◽  
Author(s):  
Max Herberhold ◽  
Silke Gerstmann ◽  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
The Novel ◽  
Tin Compounds ◽  
Structural Assignment

Abstract Bis(sulfurdiimido)tin compounds of the type R2Sn[(NSN)tBu]2 [R = Me (2a), Et (2b)] re­ act with triethylborane Et3B by rearrangement and N-ethylation to give the novel aminoborane derivatives R2Sn[N(tBu)SN(Et)BEt2]2 (5a, b), in the same way as nBu3Sn(NSN)tBu (1) reacts with Et3B to give nBu3Sn[N(tBu)SN(Et)BEt2] (4). In contrast, 2c (R = tBu) and tris(sulfurdiimido)tin compounds RSn[(NSN)tBu]3 [R = Me (3a), nBu (3d)] react with Et3B mainly by Sn- and S-ethylation, accompanied by extensive decomposition. 1H, 11B , 13C, 15N and 119Sn NMR spectroscopy served for the structural assignment in solution.

Structural assignment of conductive polymers by CP/MAS 13C-NMR

1991 ◽  
Vol 41 (1-2) ◽  
pp. 305-308 ◽  
Author(s):  
J. Nouwen ◽  
D. Vanderzande ◽  
H. Martens ◽  
J. Gelan ◽  
Y. Zhou ◽  
...  
Keyword(s):  
13C Nmr ◽  
Conductive Polymers ◽  
Structural Assignment ◽  
Cp Mas 13C Nmr
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