Tricyclic spirodienones via intramolecular radical phenol–nitronic acid coupling

1991 ◽  
pp. 899-900 ◽  
Author(s):  
David Hobbs-Mallyon ◽  
Donald A. Whiting
Keyword(s):  
Nitronic Acid

Enantioselective Approaches to 3,4-Annulated Indoles Using Organocatalytic Domino Reactions

Synlett ◽  
2017 ◽  
Vol 28 (13) ◽  
pp. 1530-1543 ◽  
Author(s):  
Mariafrancesca Fochi ◽  
Luca Bernardi ◽  
Lorenzo Caruana
Keyword(s):  
Phosphoric Acid ◽  
Reaction Pathway ◽  
Ergot Alkaloids ◽  
Acid Catalyst ◽  
Secondary Amines ◽  
Domino Reactions ◽  
Structural Framework ◽  
Unique Reaction ◽  
Iminium Ions ◽  
Nitronic Acid

Organocatalytic domino reactions of 4-substituted indoles are summarized in this account. Two reactions have been developed, one with enals, activated by secondary amine catalysts via iminium ions, and one with nitroethene, using a phosphoric acid catalyst. Both reactions required solving the challenge posed by the very low nucleo­philicity of the indole substrates, which bear an electron-withdrawing Michael acceptor at C4. DFT calculations were used to shed light on the unique reaction pathway followed by the phosphoric acid catalyzed transformation, wherein a bicoordinated nitronic acid intermediate was found to evolve preferentially through an intramolecular nitro-Michael reaction, instead of the common tautomerization pathway. These reactions provide new and efficient entries to 3,4-ring-fused indoles in dia­stereo- and enantioenriched form. In more detail, the structures obtained feature a 1,3,4,5-tetrahydrobenzo[cd]indole core, which is present in the structural framework of ergot alkaloids. Indeed, the preparation of an intermediate previously used in ergot alkaloid (6,7-secoagroclavine) synthesis was possible from one of the catalytic adducts.1 Introduction2 Reactions of 4-Substituted Indoles with α,β-Unsaturated Aldehydes Catalyzed by Secondary Amines3 Reactions of 4-Substituted Indoles with Nitroethene Catalyzed by Brønsted Acids4 Conclusion

Formation and decay of nitronic acid in the photorearrangement of o-nitrobenzyl esters

1987 ◽  
Vol 39 (2) ◽  
pp. 317-332 ◽  
Author(s):  
Q.Q. Zhu ◽  
W. Schnabel ◽  
H. Schupp
Keyword(s):  
Nitronic Acid

scholarly journals The Salts of Nitronic acid as CO2-Corrosion Inhibitors

2014 ◽  
Vol 10 (8) ◽  
pp. 3042-3052
Author(s):  
Abbasov V. M. ◽  
Aliyeva L. I. ◽  
Haciyeva S. J. ◽  
Mursalov N. I.
Keyword(s):  
Protective Effect ◽  
Corrosion Inhibitor ◽  
Corrosion Inhibitors ◽  
Isopropyl Alcohol ◽  
Protective Layer ◽  
Co2 Corrosion ◽  
Isomeric Structure ◽  
Branched Structure ◽  
Higher Olefins ◽  
Nitronic Acid

The salts of nitronic acids were obtained by nitration of higher olefins, both normal and isomeric structure in the presence of aqueous alkali. The resulting salts (Na+, K+, NH4+), were tested in CO2 -media as a corrosion inhibitor. The results showed that, the protective effect of the linear nitronated olefins increases by increasing the number of carbon atoms. This is due to the fact that because of  the branched structure of the compounds, it is much more difficult to form a dense protective layer on the metal surface. 20% solutions of nitronated ethanolamine in isopropyl alcohol was synthesized and tested as corrosion inhibitor in carbon dioxide environments. The results showed that diethanolamine nitron based on a mixture of normal olefins C16-C18 at a concentration of 50 ppm has a high protective effect of  99.69%.

scholarly journals An Unusual Course of a Nitro Sugar Acetylation: Formation of a Crystalline Nitronic Acid – Acetic Acid Mixed Anhydride

1971 ◽  
Vol 49 (19) ◽  
pp. 3236-3238 ◽  
Author(s):  
Werner Rank ◽  
Hans H. Baer
Keyword(s):  
Acetic Acid ◽  
Acetyl Chloride ◽  
Acetyl Derivative ◽  
Acid Anhydride ◽  
Mixed Anhydride ◽  
Nitronic Acid

Whereas acetylation of methyl 4,6-O-benzylidene-3-deoxy-3-nitro-β-D-mannopyranoside (1) and its β-D-galacto isomer 2 with acetyl chloride and triethylamine in ether furnished the expected 2-O-acetylated nitro glycosides, 1a and 2a, the same method applied to the α-D-talo isomer 3 gave the 2-O-acetyl derivative of the corresponding nitronic acid – acetic acid anhydride, 4.

Transient nitronic acid formation in the protonation of the carbanion of 2,2′,4,4′-tetranitrodiphenylmethane in acidic methanol

1987 ◽  
Vol 65 (8) ◽  
pp. 1980-1986 ◽  
Author(s):  
François Terrier ◽  
Jacques Lelièvre ◽  
Alain-Pierre Chatrousse ◽  
Robert Schaal ◽  
Patrick G. Farrell
Keyword(s):  
Carboxylic Acid ◽  
Solvent Effects ◽  
Rate Constants ◽  
Intrinsic Rate ◽  
Low Ph ◽  
The Other ◽  
Acid Formation ◽  
Other Hand ◽  
Protonated Species ◽  
Nitronic Acid

Rates of deprotonation of 2,2′,4,4′-tetranitrodiphenylmethane (1) by a variety of bases B− and of protonation of the resulting carbanion (2) by the conjugated acids BH in methanol have been measured at 20 °C. The Brønsted αBH coefficients for protonation of 2 by phenol and carboxylic acid buffers are equal to 0.58 and 0.43, respectively, as compared with αBH values of 0.59 and 0.52 respectively, for the same reactions in 50% H2O – 50% DMSO. On the other hand, a comparison of the intrinsic rate constants [Formula: see text] (in the Marcus sense) in the two solvents reveals that the effect of going from 50% H2O – 50% DMSO to methanol is to lower [Formula: see text] for the phenol reactions by a factor of 2 but to increase [Formula: see text]for carboxylic acid reactions by a factor of 5. It is shown that the solvent effects on αBH and [Formula: see text] can all be understood in the context of the Principle of Imperfect Synchronisation (PIS) recently proposed by Bernasconi. In addition, a fast equilibrium protonation of the carbanion 2 is found to precede its conversion to 1 at low pH, i.e., pH < 5. The resulting protonated species is suggested to be the nitronic acid 2,H arising from fast protonation of a para NO2 group of 2. The [Formula: see text] value associated with the ionization of 2,H is ∼4.25.

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