scholarly journals Regioselectivity and Tautomerism of Novel Five-Membered Ring Nitrogen Heterocycles Formed via Cyclocondensation of Acylthiosemicarbazides

Molecules ◽  
2008 ◽  
Vol 13 (3) ◽  
pp. 501-518 ◽  
Author(s):  
Jana Tomaščiková ◽  
Ján Imrich ◽  
Ivan Danihel ◽  
Stanislav Böhm ◽  
Pavol Kristian ◽  
...  
Keyword(s):  
Nitrogen Heterocycles ◽  
Membered Ring ◽  
Ring Nitrogen

The Variable Electronegativity Method. VII. Pyrazole, Its Anion and Cation

1960 ◽  
Vol 13 (1) ◽  
pp. 49 ◽  
Author(s):  
RD Brown ◽  
ML Heffernan
Keyword(s):  
Dipole Moment ◽  
Electron Distribution ◽  
Nitrogen Heterocycles ◽  
Chemical Properties ◽  
Membered Ring ◽  
Matrix Elements ◽  
Electron Densities ◽  
Ring Nitrogen ◽  
Made In ◽  
Tertiary Nitrogen

Results of a VESCF treatment of pyrazole, its anion, and cation are reported. A comparison is made of the chemical properties of pyrazole and those predicted from the calculated π-electron densities. An ambiguity in the comparison owing to the rapid tautomerization of pyrazole is emphasized. The calculated π-electron distribution in the anion supports the suggestion made in previous papers that the relative electronegativities of carbon and tertiary nitrogen reverse when their π-electron densities exceed 1.2. The dipole moment is predicted to be about 2.5 D for pyrazole, in agreement with observations in solution. Theoretical values of ionization potentials are also presented. An analysis is made of VESCF matrix elements and some empirical guides as to suitable values of coulomb and resonance parameters for five-membered ring nitrogen heterocycles are suggested.

scholarly journals Synthesis and properties of seven- to nine-membered ring nitrogen heterocycles. Cyclic amidines and cyclic amidinium salts

ARKIVOC ◽  
2018 ◽  
Vol 2018 (1) ◽  
pp. 288-318 ◽  
Author(s):  
Isabel A. Perillo ◽  
María C. Caterina ◽  
Alejandra Salerno
Keyword(s):  
Nitrogen Heterocycles ◽  
Membered Ring ◽  
Ring Nitrogen

Xanthate Transfer Cyclisation of Glycine Radicals; Synthesis of 5- and 6-Membered Ring Nitrogen Heterocycles

2010 ◽  
Vol 103 (7-8) ◽  
pp. 329-342 ◽  
Author(s):  
Jan H. Udding ◽  
J. P. M. Giesselink ◽  
Henk Hiemstra ◽  
W. Nico Speckamp
Keyword(s):  
Nitrogen Heterocycles ◽  
Membered Ring ◽  
Ring Nitrogen

ChemInform Abstract: Xanthate Transfer Cyclization of Glycine Radicals; Synthesis of 5- and 6-Membered Ring Nitrogen Heterocycles.

ChemInform ◽  
2010 ◽  
Vol 26 (14) ◽  
pp. no-no
Author(s):  
J. H. UDDING ◽  
J. P. M. GIESSELINK ◽  
H. HIEMSTRA ◽  
W. N. SPECKAMP
Keyword(s):  
Nitrogen Heterocycles ◽  
Membered Ring ◽  
Ring Nitrogen

ChemInform Abstract: Medium-Ring Nitrogen Heterocycles

ChemInform ◽  
2010 ◽  
Vol 23 (8) ◽  
pp. no-no
Author(s):  
P. A. EVANS ◽  
A. B. HOLMES
Keyword(s):  
Nitrogen Heterocycles ◽  
Ring Nitrogen ◽  
Medium Ring
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