Chiral semicorrins and related nitrogen heterocycles as ligands in asymmetric catalysis

1993 ◽  
Vol 26 (6) ◽  
pp. 339-345 ◽  
Author(s):  
Andreas Pfaltz
Keyword(s):  
Asymmetric Catalysis ◽  
Nitrogen Heterocycles

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

Evaluation of Antioxidant and Antitumor Activities of Some Prepared Nitrogen Heterocycles

2011 ◽  
Vol 3 (7) ◽  
pp. 106-110
Author(s):  
Mohamed Abd El-Moneim ◽  
◽  
Ibrahim M El-Deen ◽  
Wessam Abd El-Fattah
Keyword(s):  
Nitrogen Heterocycles ◽  
Antitumor Activities

Chiral Bipyridine Derivatives in Asymmetric Catalysis

2003 ◽  
Vol 7 (17) ◽  
pp. 1737-1757 ◽  
Author(s):  
A. Malkov ◽  
P. Kocovsky
Keyword(s):  
Asymmetric Catalysis
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