ChemInform Abstract: ACID-CATALYZED CYCLIZATION OF 2-HYDROXY-3-PYRROLONE DERIVATIVES. 2-METHOXY-3(2H)-FURANONES AS PRECURSORS OF POLYCYCLIC NITROGEN HETEROCYCLES

1985 ◽  
Vol 16 (39) ◽  
Author(s):  
J. P. FREEMAN ◽  
M. K. FETTES-FIELDS
Keyword(s):  
Nitrogen Heterocycles ◽  
Acid Catalyzed

Brønsted acid-catalyzed, enantioselective synthesis of 1,4-dihydroquinoline-3-carboxylates via in situ generated ortho-quinone methide imines

2017 ◽  
Vol 15 (17) ◽  
pp. 3706-3716 ◽  
Author(s):  
Tomáš Hodík ◽  
Christoph Schneider
Keyword(s):  
Phosphoric Acid ◽  
Acid Catalysis ◽  
Nitrogen Heterocycles ◽  
Enantioselective Synthesis ◽  
Quinone Methide ◽  
Keto Esters ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Straightforward Approach

A straightforward approach toward the synthesis of a broad range of 1,4-dihydroquinoline-3-carboxylates is described. Under phosphoric acid catalysis in situ-generated ortho-quinone methide imines reacted with β-keto esters to form the nitrogen heterocycles with good chemical yields and enantioselectivities.

Organocatalyzed [3+3] Annulations for the Construction of Heterocycles

Synthesis ◽  
2020 ◽  
Vol 52 (08) ◽  
pp. 1181-1202
Author(s):  
Yannan Zhu ◽  
You Huang
Keyword(s):  
Nitrogen Heterocycles ◽  
Heterocyclic Carbenes ◽  
Secondary Amines ◽  
Tertiary Amines ◽  
Lewis Bases ◽  
Hydrogen Bonding Interactions ◽  
Chiral Phosphoric Acid ◽  
Oxygen Heterocycles ◽  
Sulfur Heterocycles ◽  
Acid Catalyzed

Six-membered heterocyclic systems are widely distributed in many natural products and pharmaceuticals, and the construction of highly functionalized six-membered heterocyclic compounds is an important topic in modern organic synthesis. Organocatalyzed [3+3] annulations represents an important method for assembling a substantial variety of six-membered cycles that contain one or more heteroatoms. This review describes the development of organocatalyzed [3+3] annulations for the synthesis of six-membered heterocycles, including organocatalysis using secondary amines, tertiary amines, phosphines, chiral phosphoric acids and N-heterocyclic carbenes.1 Introduction2 Secondary Amine Catalyzed [3+3] Annulations2.1 Synthesis of Nitrogen Heterocycles2.2 Synthesis of Oxygen Heterocycles2.3 Synthesis of Sulfur Heterocycles3 Tertiary Amine Catalyzed [3+3] Annulations3.1 Catalysis through Multiple Hydrogen-Bonding Interactions3.2 Catalysis of Tertiary Amines as Lewis Bases4 Phosphine-Catalyzed [3+3] Annulations4.1 Synthesis of Nitrogen Heterocycles4.2 Synthesis of Oxygen Heterocycles4.3 Synthesis of Heterocycles Containing Two or More Heteroatoms5 Chiral Phosphoric Acid Catalyzed [3+3] Annulations5.1 Synthesis of Nitrogen Heterocycles5.2 Synthesis of Heterocycles Containing Two or More Heteroatoms6 N-Heterocyclic Carbene Catalyzed [3+3] Annulations6.1 Synthesis of Nitrogen Heterocycles6.2 Synthesis of Oxygen Heterocycles6.3 Synthesis of Heterocycles Containing Two or More Heteroatoms7 Conclusion and Outlook

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.

Acid Catalyzed Furan Ring Transposition

10.1039/sp768 ◽  
2014 ◽  
Author(s):  
Jamsheena V. ◽  
Ravindra Phatake
Keyword(s):  
Furan Ring ◽  
Acid Catalyzed

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

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

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